McKEAGUE, J., delivered the opinion of the court, in which ROGERS, J., joined. MERRITT, J. (pp. 521-28), delivered a separate dissenting opinion.
OPINION
McKEAGUE, Circuit Judge.Defendant-appellant Rafael Phinazee was convicted by a jury of conspiracy to distribute crack and powder cocaine. The presentence report (“PSR”) calculated his total offense level at 38 and placed him in a criminal category of VI, which resulted in a Sentencing Guidelines range of 360 months’ imprisonment to life.1 The district court initially sentenced Phinazee to 360 months’ imprisonment. After his appeal to this court and a subsequent remand in light of United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005), he was re-sentenced to 300 months’ imprisonment. Phinazee again appealed, and now argues that his sentence is substantively unreasonable because the downward variance was not large enough. For the reasons stated below, we AFFIRM defendant’s sentence.
I. BACKGROUND
In 1997, several federal and local law enforcement agencies were involved in a long-term investigation that targeted drug traffickers in the Chattanooga, Tennessee area that resulted in over fifty convictions. In 2003, as part of that investigation, a federal grand jury indicted Rafael Phina-zee and various co-conspirators on one count of conspiracy to distribute fifty (50) grams or more of crack cocaine and 5,000 grams or more of powder cocaine, in violation of 21 U.S.C. §§ 846, 841(a)(1) and (b)(1)(A). The jury found Phinazee guilty of the drug conspiracy as charged in the indictment.
On August 20, 2004, Phinazee was sentenced to a term of 360 months’ imprisonment under the then-mandatory Sentencing Guidelines.2 Phinazee filed a timely *514notice of appeal, and on January 6, 2006, we affirmed his conviction but remanded the case to the district court for re-sentencing in light of Booker. United States v. Hereford, 162 Fed.Appx. 439, 440-41 (6th Cir.2006).
On May 11, 2006, the district court re-sentenced Phinazee to a term of 300 months’ imprisonment, five years below the bottom of the now-advisory Sentencing Guidelines range.3 The Amended Judgment was entered. Phinazee previously had filed a timely notice of appeal on May 16, 2006.
II. ANALYSIS
On appeal, Phinazee argues his sentence of 300 months is substantively unreasonable. In Booker, the Supreme Court declared the once mandatory Sentencing Guidelines to be advisory in nature. 543 U.S. at 245, 125 S.Ct. 738. The Booker Court further announced that the proper standard of appellate review for criminal sentencing appeals is reasonableness. Id. at 260-62, 125 S.Ct. 738. Our reasonableness review is two-fold, requiring that a sentence be both procedurally and substantively reasonable. United States v. Davis, 458 F.3d 491, 495 (6th Cir.2006). A sentence may be procedurally unreasonable if the district court “did not appreciate the non-mandatory nature of the guidelines, did not correctly calculate the sentencing range under the guidelines, or did not consider the § 3553(a) factors.” Id. (citations omitted). “[A] sentence may be substantively unreasonable when the district court selects the sentence arbitrarily, bases the sentence on impermissible factors, fails to consider pertinent § 3553(a) factors or gives an unreasonable amount of weight to any pertinent factor.” United States v. Borho, 485 F.3d 904, 908 (6th Cir.2007) (citation and quotation marks omitted).
We review the reasonableness of a sentence using the abuse-of-discretion standard of review. Gall v. United States, — U.S. -, 128 S.Ct. 586, 594, 169 L.Ed.2d 445 (2007). If defendant’s sentence is within the Sentencing Guidelines range, we may, but need not, apply a presumption of reasonableness. Id. at 597 (citation omitted). Where, as here, a defendant’s sentence is outside the Sentencing Guidelines range, either above or below it, we cannot apply a presumption of unreasonableness. Id. Nonetheless, we “may consider the extent of the deviation, but must give due deference to the district court’s decision that the § 3553(a) factors, on a whole, justify the extent of the variance.” Id. Indeed, “[t]he fact that the appellate court might reasonably have concluded that a different sentence was appropriate is insufficient to justify reversal of the district court.” Id. As we explained in Kirchhof:
This case is unusual because the appellant is a defendant who argues that the downward variance from the reeom-*515mended guidelines range that he received is unreasonable because it is not large enough.
See United States v. Kirchhof, 505 F.3d 409, 414 (6th Cir.2007) (citation omitted) (an analogous pre-Gall decision because the defendant argued the variance was not large enough and this court applied a nonrigid form of the proportionality analysis that does not run afoul of Gall’s admonitions to determine the sentence was reasonable).
Phinazee does not contend that the district court selected his sentence arbitrarily, based its decision on impermissible factors, or failed to consider pertinent § 3553 factors. Rather he asserts the district court’s sentence was substantively unreasonable inasmuch as it improperly deferred to the Sentencing Guidelines with respect to two of the factors, namely deterrence and retribution, and that the court improperly weighed those same factors over the others.
First, Phinazee argues that the district court should have made a specific finding that stated the reasons it rejected applying a ten year sentence as permitted for violators of 21 U.S.C. § 841(b)(1)(A). He cites no authority for the proposition that a district court must make a specific finding about why it imposed a sentence higher than the statutory minimum. As the government notes, the statutory minimum is not a sentencing factor. See 18 U.S.C. § 3553(a). In any event, the ten-year minimum sentence that appellant repeatedly relies on is not the appropriate benchmark. Here, as the government explains, it could have filed a notice of enhancement pursuant to 21 U.S.C. § 851 because Phinazee had at least two prior felony drug convictions. Such an enhancement would have subjected Phinazee to a statutory mandatory sentence of life imprisonment, not a ten-year sentence. See 21 U.S.C. § 841(b)(1)(A) (“If any person commits a violation of this subparagraph ... after two or more prior convictions for a felony drug offense have become final, such person shall be sentenced to a mandatory term of life imprisonment without release.”). Moreover, Congress has indicated that career offenders, like Phinazee, should be sentenced at or near the maximum term of imprisonment, which is life here. See 28 U.S.C. § 994(h). The district court explicitly recognized its obligation to impose a sentence sufficient but not greater than necessary to comply with the purposes set forth in § 3553(a) before it imposed defendant’s sentence. That the district court did not also explicitly reject the statutory minimum is of no consequence. See United States v. Gale, 468 F.3d 929, 940 (6th Cir.2006) (stating a district court is not required to explain “why an alternative sentence was not selected”).
Second, Phinazee objects to the district court’s reliance on general deterrence rather than specific deterrence. He argues the district court failed to “consider how deterrence would adequately be promoted on the circumstances of this case.” Appellant’s Br. at 23. We addressed an analogous argument in United States v. Turner, 173 Fed.Appx. 402, 407-08 (6th Cir.2006) (reviewing for plain error and finding that general deterrence is an acceptable basis for sentencing). Under § 3553, the district court may impose a sentence “to afford adequate deterrence to criminal conduct.” 18 U.S.C. § 3553(a)(2)(B). The Turner court’s analysis is persuasive in this respect:
The plain language of the statute-that courts may “afford adequate deterrence” in sentencing-also militates against limiting the authority of the court to specific deterrence. Nothing in the explicit language indicates a congressional intent to limit the court’s authority. We note *516that this conclusion comports with the longstanding and uncontroversial practice of considering general deterrence in sentencing. See United States v. Barbara, 683 F.2d 164, 167 (6th Cir.1982) (noting traditional use of both specific and general deterrence).
Turner, 173 Fed.Appx. at 408; see also United States v. Blackwell, 459 F.3d 739, 774 (6th Cir.2006) (affirming a defendant’s sentence where the district court in its § 3553(a) analysis stated that it doubted the defendant would ever engage in the conduct again, but that a primary sentencing factor was the need “to deter other similarly situated” individuals from engaging in the conduct). Here, the district court found that:
The reality is, here in Chattanooga and in most other cities in this nation, there are young men who grew up in circumstances such as Mr. Phinazee related. These young men are all tempted to involve themselves in selling drugs because it is easy to do. Drugs are plentiful, and you can make money from doing it. Many of these young men have drug habits themselves, and they use the proceeds from their trafficking activities to support their own drug habit. That is a problem in this country. So the issue becomes, what type of sentence is necessary to tell these young men who are dropping out of high school, who are not going to work, who are doing other things that are not desirable socially, that if you engage yourself in the type of activity that Mr. Phinazee involved himself in ... that you will receive such a punishment that they will be deterred from engaging in that punishment.
J.A. 143^44. Accordingly, the district court did not err by relying on general deterrence considerations when it sentenced Phinazee.
Next, Phinazee objects to the district court’s explicit reliance on Congress and the Sentencing Commission as to the deterrence and retribution factors.4 Phi-nazee’s argument is unpersuasive because the Sentencing Guidelines range is an explicit factor that a district court must consider in its sentencing analysis. See 18 U.S.C. § 3553(a)(4); see also Gall, 128 S.Ct. at 596 (stating “the Guidelines should be the starting point and the initial benchmark”); Gale, 468 F.3d at 934 (stating that “[ajlthough the Guidelines are now advisory, rather than mandatory, the district court must still consider the Guidelines in fashioning a defendant’s sentence”). While the district court here stated it would defer to a within Sentencing Guidelines range sentence upon consideration of two § 3553 factors, after consideration of the other factors it determined that a lower than Sentencing Guidelines range sentence was warranted. See United States v. Buchanan, 449 F.3d 731, 734 (6th Cir.2006) (affirming a sentence wherein the district court stated that after “[cjonsider-ing and weighing” all the § 3553(a) factors they “weigh in favor of a Guideline sentence” with the exception of one factor); United States v. Cage, 458 F.3d 537, 543 (6th Cir.2006) (holding that the district *517court did not err in viewing the Sentencing Guidelines as a starting point before weighing the Sentencing Guidelines in relation to other § 3558(a) factors). The district court’s approach was proper and Phinazee cites no authority to suggest otherwise. In this case, Phinazee’s argument is particularly problematic because the district court varied downward five years, and yet, he complains that the variance was not large enough.
To the extent Phinazee and the dissent argue that the district court did not weigh rehabilitation enough in its sentencing analysis, such an argument similarly fails. See United States v. Perry, 228 Fed.Appx. 557, 559 (6th Cir.2007) (“Rehabilitation is but one factor, however. The district court must consider all the factors, but need not necessarily ‘engage in a ritualistic incantation’ of the factors.” (quoting United States v. Chandler, 419 F.3d 484, 488 (6th Cir.2005))). Here, the district court engaged in the prudent balancing of relevant factors that § 3553(a) contemplates. The district court found that:
The next job for the Court, then having articulated its reasons and these four factors, is to balance these factors. The parsimony provision in Section 3553(a) instructs the Court that it should impose a sentence sufficient but not greater than necessary to comply with the purposes that I have just stated.
The Court, after taking into account the nature and circumstances of the offense and the history and characteristics of the defendant!)], concludes that [a] sentence!] slightly less than the sentence! ] the Court imposed initially would be sufficient to achieve the purposes. The primary consideration, again, is retribution and general deterrence. So the Court has given heavy weight to those two, but yet the Court has balanced those against the Court’s assessment of the need for rehabilitation and the need to incapacitate you....
!T]he Court will impose a sentence of 300 months.... That’s a reduction of five years....
The Court believes that [this] sentence! ], even though [it is] less than the guideline range that the Court calculated, [is] adequate to reflect the seriousness of the offense, to promote respect for the law, to provide just punishment for the offense, and to afford adequate deterrence to others who might be inclined to involve themselves in this type of criminal conduct.
The Court does not believe the need to protect the public from future crimes of these two defendants is so great that a harsh sentence should be imposed. The court also believes that the need to afford the defendant!] rehabilitation is not so great. And the Court’s assessment of the these last two factors the Court has balanced against the earlier two to persuade the court that some reduction is necessary.
J.A. 145-46 (emphasis added); see also J.A. 142^13 (“So to the extent that further rehabilitation is needed for rehabilitation, the Court does not believe that should be a major factor. The Court sees the need for rehabilitation in this case as being small.”). In particular, with respect to Phinazee’s addiction issues, the district court ordered that he receive a 500-hour residential institution drug treatment program while he is incarcerated. J.A. 148.
To the extent Phinazee argues the district court ignored his post-offense rehabilitation, his argument similarly fails. In Davis, the court addressed a variance downward to one day from a Sentencing Guidelines range of 30 to 37 months. 458 F.3d at 497. “One of the featured grounds for the variance -the 14-year gap between *518Davis’s crimes and his second sentencing hearing-does not support such a dramatic variance (and indeed may not support a variance at all).” Id. The court explained that:
Time intervals of this sort appear nowhere in the list of § 3553(a) factors. The underlying prosecution occurred within the statute-of-limitations period. And, Davis has not raised any speedy-trial objections to the prosecution. Nor, at any rate, is it invariably clear when a legal delay in prosecuting or sentencing an individual becomes a friend or foe of the defendant. What criminal suspect, after all, wants the government (and the grand jury) to pull the indictment trigger too quickly?
Id. That said, the delay between the “time a crime is committed and the time a guilty defendant serves his sentence of course should not be casually ignored” because “it may allow him to show demonstrable signs of rehabilitation.” Id. at 497-98 (emphasis added). The district court heard argument from defendant’s counsel addressing rehabilitation during the time period between the indictment and the sentencing. See, e.g., J.A. 124-35 (“Five years after this conspiracy wound up, he’s indicted by the government and hauled into court. During the pendency of that five years, Mr. Phinazee, of course, is still an addict, but during the pendency of that five years, he seeks drug treatment ..., he gets a GED, he goes to college ... he starts his own business; he tries twice, actually.”). Yet, the district court also heard the government’s response to Phinazee’s rehabilitation claims and was entitled to weigh it with all the other factors. See, e.g., J.A. 129 (“[Defendant’s counsel] argues [sic] that this gentleman has turned his life around. I respectfully beg to differ, Your Honor. Mr. Phinazee didn’t learn a lesson, never learned a lesson, to this day hasn’t learned a lesson.”); J.A. 130 (referring to the PSR and emphasizing that no income was reported to the Social Security Administration from 2001 to 2004).5 Indeed, this argument was not ignored here and, as discussed infra, rehabilitation was, in part, the grounds for the district court’s downward variance. That the district court did not explicitly explain why a larger variance was not warranted is of no consequence. See Gale, 468 F.3d at 943. Indeed, we have explained that:
[A] district court need not describe in detail or list all the documents or other evidence it considered during sentencing. It is fair to say that if an appellate court cannot rely on a lower court to do its duty by reviewing the factual record, our system of justice will collapse of its own weight. There is a presumption in the law that a district court knows and applies the law correctly, and a similar presumption must extend to the court’s factual review of the record. Thus, without some affirmative indication in the record to the contrary (apart from the sentence imposed), we presume that a district court has reviewed the evidence provided to it.
*519Id. at 941 (citation omitted); see also Rita v. United States, — U.S. —, 127 S.Ct. 2456, 2468-69, 168 L.Ed.2d 203 (2007) (stating a district court need not provide an explanation for rejecting a mitigating argument if “the matter is conceptually simple” and “the record makes clear that the sentencing judge considered the evidence and arguments”); United States v. Pettie, 242 Fed.Appx. 313, 317 (6th Cir.2007) (stating that a district court need not discuss a type of “regular, recurring circumstance” absent a showing of the exceptional aspects of that circumstance).
Moreover, Phinazee’s rehabilitation is not atypical or exceptional such that it warrants a variance larger than the five years already granted by the district court. Cf. United States v. Allman, 119 Fed.Appx. 751, 755 (6th Cir.2005) (stating “[o]nly exceptional rehabilitation can support a downward departure”). Even if we would have varied down more than five years, “our review is not de novo and we cannot conclude that the sentence imposed by the district court is substantively unreasonable.” United States v. Cherry, 487 F.3d 366, 372 (6th Cir.2007). “The bottom line is that when deciding questions of ‘substantive unreasonableness’ in the post-Booker, advisory-Guidelines world, we must continue to be wary of substituting our judgment for that of the district court.” United States v. Hairston, 502 F.3d 378, 385-86 (6th Cir.2007).
The dissent asserts that Phinazee’s sentence “is particularly harsh in light of the sentencing judge’s reasonable statement to Phinazee from the bench that based on considerations of ‘rehabilitation’ and ‘incapacitation’ alone, Phinazee deserved only a short sentence.” First, we are unclear what the dissent considers a “short” sentence. Regardless, the district court simply did not say or infer that Phinazee deserved a short sentence. Rather, what the district court said was that it did not believe that the need for additional rehabilitation or incapacitation “should be a major factor” in determining Phinazee’s sentence. J.A. 143. Presumably, this is precisely why the district court varied downward five years from the bottom of the applicable Sentencing Guidelines range and imposed a 300-month sentence. Phi-nazee points us to no factors that would require the imposition of an even shorter sentence. Cf. Kirchhof, 505 F.3d at 415 (finding “[njone of the other factors to which Kirchhof directs the court are so compelling as to necessitate a shorter sentence”). Indeed, in asking us to find his sentence unreasonable, Phinazee and the dissent fail to direct our attention to a single case in this circuit in which upon a Booker remand that resulted in a downward variance from the initial sentence and the Sentencing Guidelines range, we nonetheless found the sentence substantively unreasonable because that variance was not large enough. While Phinazee’s “sentence was lengthy, he has not established that the sentence was unreasonable.” United States v. Ward, et. al., 506 F.3d 468, 478 (6th Cir.2007) (citation omitted).
We pause to respond to some of the dissent’s other comments. The dissent argues that judicial fact-finding used to ratchet up the sentence here implicates the Sixth Amendment. We first note that Phi-nazee himself did not even raise a Sixth Amendment objection to the use of judicial fact-finding and therefore it is waived. However, even if it were not waived, any such argument ignores the straightforward import of the Supreme Court’s ruling in Rita. In response to Rita’s objection to appellate courts applying a nonbinding presumption of reasonableness to a within-Guidelines range sentence, the Supreme Court explained:
*520In our view, however, the presumption, even if it increases the likelihood that the judge, not the jury, will find “sentencing facts,” does not violate the Sixth Amendment. This Court’s Sixth Amendment cases do not automatically forbid a sentencing court to take account of factual matters not determined by a jury and to increase the sentence in consequence.
Rita, 127 S.Ct. at 2465-66. Accordingly, any Sixth Amendment claim here is merit-less.
The dissent also suggests that Phi-nazee’s sentence was too harsh in comparison to his codefendant and supplier, Lindsey Morris. In his statement of issues submitted for review, Phinazee argues in a similar vein that “the career-offender provision of the Guidelines should not be followed as it results in a grossly disproportionate sentence when compared to those with the greatest level of culpability for the offense.” Appellant’s Br. at 4. Yet, he fails to present even the slightest argument on this point. Because issues “adverted to on appeal in a perfunctory manner unaccompanied by some effort at developed argument are deemed waived,” we need not address the issue. United States v. Demjanjuk, 367 F.3d 623, 638 (6th Cir.2004) (citation and quotation marks omitted); see also United States v. Mick, 263 F.3d 553, 567 (6th Cir.2001) (deeming the defendant’s Fifth Amendment argument waived because it was summarily raised in the brief without any accompanying argument). In any event, this argument fails. To be sure, Morris received a lower sentence than Phinazee based on downward departure for substantial assistance and Phinazee’s conviction was his fourth felony drug conviction, eleventh felony conviction, and he had eighteen other arrests not reflected in his criminal history score. Phinazee and the dissent fail to recognize that unwarranted disparities in sentencing is what should be avoided, not those that are warranted. See 18 U.S.C. § 3553(a)(6) (sentencing courts shall consider “the need to avoid unwarranted sentence disparities among defendants with similar records who have been found guilty of similar conduct”); Cf. Gall, 128 S.Ct. at 600 (“[I]t is perfectly clear that the District Judge considered the need to avoid unwarranted disparities, but also considered the need to avoid unwarranted similarities among other co-conspirators who were not similarly situated.”). Moreover, even assuming the district court did not apply the career offender enhancement to raise Phi-nazee’s criminal history category to VI, the applicable Sentencing Guidelines range would have been the same under category V (i.e., 360 months to life). What is more, the PSR did not use the offense level calculated from the career offender provision because his adjusted offense level was higher without it. Accordingly, any arguments that Phinazee’s career offender status artificially inflated his sentence or that his sentence was unfairly disproportionate to others fail. See United States v. Johnson, 445 F.3d 339, 343 (4th Cir.2006) (“[B]y devising a recommended sentencing range for every type of misconduct and every level of criminal history, the Guidelines as a whole embrace ‘the need to avoid unwarranted sentence disparities among defendants with similar records who have been found guilty of similar conduct.’ ”) (quoting 18 U.S.C.A. § 3553(a)(6)).
Finally, the district court here did not engage in “rote sentencing” of Phinazee, irrespective of the dissent’s suggestion to the contrary. Rather, after the Booker remand, it held a re-sentencing hearing and imposed a sentence that varied downward five years from the lowest end of the applicable Sentencing Guidelines range. *521Our review of the hearing transcript confirms that the district court properly considered the relevant sentencing factors and provided a reasoned explanation for the sentence.
The bottom line is that Phinazee and the dissent want this court to decide afresh whether Phinazee’s circumstances warrant a larger variance or whether the sentence is reasonable, yet the Supreme Court squarely has forbidden the Courts of Appeals from engaging in that type of review. See, e.g., Gall, 128 S.Ct. at 602 (“But it is not for the Court of Appeals to decide de novo whether the justification for a variance is sufficient or the sentence reasonable. On abuse-of-discretion review, the Court of Appeals should have given due deference to the District Court’s reasoned and reasonable decision that the § 3553(a) factors, on the whole, justified the sentence.”). Indeed, it seems odd for the dissent to rely so heavily on the Supreme Court’s recent rulings in Rita, Gall, and Kimbrough when the clear, overriding import of those cases is that appellate courts must respect the role of district courts and stop substituting their judgment for that of those courts on the front line. If the dissent’s term of “guidelinitis” ever reaches mainstream use, maybe Merriam-Webster will include it as an example for its definition of “irony.”
III. CONCLUSION
For all the aforementioned reasons, we AFFIRM defendant’s sentence.
. The 2003 version of the Sentencing Guidelines was used in this case.
.. In Phinazee’s initial sentencing, the PSR identified his criminal activity as conspiracy *514to distribute at least 680 grams of crack cocaine, which resulted in a base offense level of 36. A two-level enhancement was applied for possession of a firearm in connection with the drug offense, resulting in an adjusted offense level of 38. He was adjudicated a career offender based on three prior felony drug convictions. The PSR used the higher adjusted offense level of 38 because under the career offender provision the offense level was 37. Phinazee had a total of 11 criminal history points, placing him in criminal history category V. Because Phinazee was a career offender, his criminal history category was enhanced to VI. Based on a total offense level of 38 and a criminal category of VI, Phina-zee's Sentencing Guidelines range was 360 months’ imprisonment to life.
. The PSR from the initial sentencing was used by the district court for the re-sentencing.
. To the extent this argument could be construed as procedural unreasonableness, it fails for the reasons explained infra. The characterization of “substantive” or "procedural” here is not dispositive. See United States v. Malone, 503 F.3d 481, 484 (6th Cir.2007) (recognizing that a categorization as “procedural, substantive, or a combination of the two” is irrelevant where the issue was reliance on an impermissible factor). The district court appreciated the non-mandatory nature of the Sentencing Guidelines as evidenced by its downward variance. Moreover, Phinazee does not argue the district court incorrectly calculated the Sentencing Guidelines range or failed to consider the factors set forth in § 3553(a).
. We also note that at Phinazee's initial sentencing hearing his post-offense rehabilitation was extensively discussed. See, e.g., Initial Sentencing Tr. 56:5-59:19; 63:4-65:3; 67:4-75:22. In particular, the government stated that within the post-offense time period, the government had evidence of "at least two buys off this man.” Id. at 71:13-21. The district court inquired whether the government was prepared to put on such evidence and the government agreed to do so after a short recess. Id. at 73:21-74:25. Upon resuming the hearing, the government stated that it had turned over to defense counsel "documents relative to the events that I indicated for the court” and defense counsel proceeded to “withdrawn the motion for downward departure.” Id. at 75:11-22.