J:
Typically such retro full reviews are generated if the lender has either a failed loan or they have deep reason to suspect the veracity of the original report.
Make VERY sure your review report is fully Std 3 compliant and has the documentation IN the workfile to back each and every statement and adjustment you place in your review. This kind of report may lead to face time in court... OH YEAH - make sure you state that any further personal attendance required of you as a result fo your review will be at a compensation rate of ___your normal fee.
If you have full interior access, document with additional photos... but do NOT presuppose that the interior condition today is the same as of the effective date. It is stone amazing how badly a motivated party can trash a property. You gotta give the appraiser the benefit of the doubt, unless there is clear evidence indicating the place was a complete pit as of the effective date!
I LOVE retro field reviews, as long as I can get the full scoop on what was going on back then

. 12-24 months back isn't bad, cause you probably have GOOD MLS data and can take a good look at the closed sales AND "what was active but closed subsequent to the effective date" by doing a little tweaking of he MLS records!
The important things are to make sure that you are looking at the speciific time frame of the EFFECTIVE DATE. You don't get perfect 20/20 foresight when you do a present time appraisal: you don't know what sales will close or at what price, don't expect the original appraiser to have such foresight either!
You CAN however look at what sales were actively listed as of the effective date to insure that you have a good handle on the principal of substitution some data systems make this easier than others.
I do put a little more work into the nuts and bolts of verification... interviewing at LEAST one of the principals in each transaction used in the report and any that I elect to use as alternate comparables (if I wholly disagree with the original appraisers choice-es)