....and there's a lot of things that USPAP does not go "into"....
No perfect market.....no perfect adjustments. There is paired sales analysis when those ideal properties fall within your current review of available (sale) data to support your report. Outside of the desire for perfection.....there is always the Reasonableness Test, and there may be the cost of an amenity or an upgrade or an update, but we all know that cost does NOT equal value.....unless the client is attempting to shove cost-to-cure down your throat and their customer is desparate.
Enter, Scope of Work, and remember that S.o.W. has granted permission for reports to be grossly down-sized, and for development detail and expended time therefor to also be down-sized. Many times the client receives credible adjustments from one's grid.....just from one's years of experience in the local market, conversations with agents affiliated with the marketing-negotiation-sale of those most-similar, most-proximate and most-recent sales that you gleaned from your database search.
Step outside of most-similar, most-proximate and most-recent.....and one tip-toes into that greater minefield where adjustments are certain to need more explanation and more "workfile support" if feet get pressed to the fire. We return then to the Reasonableness Test, and what adjustment amounts one's peers would conclude and apply. If you would apply $5,000 to $10,000 to that 3rd garage space, and 3 independantly chosen and unbiased reviewers who work in that same market were to agree that such an adjustment is reasonable, then one can say that the original appraiser was NOT out-of-line.
Enter a 4th reviewer, from a different market, who might have an agenda or else is not anchored in common sense and reasonableness.....then such a reviewer might very well cause a stink about someone else's adjustments. It really can be a luck-of-the-draw situation sometimes with who reviews YOUR report. The quality of the reviewer is as important and significant as the quality of the (original) appraiser. A well-researched appraisal, using most-similar, most-proximate, most-recent sales, and with a coherent grid and crystal clear text components explaining that which needs to be explained......should deflect most any UNreasonable review that declares that PERFECTION was not presented in the report. Expect every report you do to get reviewed by a Review Nazi. Don't send it out unless you can defend every element you present.
Enter......the grossly minimized S.o.W., the rapidly-completed report, the low fee that DROVE a lesser quality and we get what is certain to rise to the surface with greater frequency in the coming 1 to 2 to 3 years. Isn't it reassuring to know that Desktop Reports, new-form Drive-By's, AVM's, BPO's and other cheaper alternative valuation substitutes MIGHT NOT REQUIRE one to make "perfect" adjustments, let alone explain them, since "satisfactory for the user" permits lower quality to be mislabeled as "dont' worry, we had the place appraised" !