Who chooses your clients? You do! Everyone is absolutely right - it SHOULD be one way, and always seems to be another.
Trainees have little choice about who they work for, but they still have a choice. In my experience, the supervisory appraiser is frequently guilty of bad training and the trainee won't even realize it until he or she submits his experience for a state license or certification.
Financial institutions do indeed use a "checklist." They also use incompetent reviewers because appraisal review is not a priority and they think they are savings themselves money.
Today I called Fannie Mae about a major AMC that has thousands of clients. The AMC violates every rule in the book by ordering desk reviews of residential reports and asking for a value "recommendation", ordered from their approved appraisers. The form they use was developed in 1988 and says so right on the form. A New Jersey appraiser cut the value conclusion reached by one of my roster appraisers from $570,000 to $300,000 without ever supporting the "recommendation." My poor client - its investor recommended requesting the review and suggested which AMC, implying that the review would make the file acceptable despite some larger than typical (read: exceeding guidelines) in the original appraisal (which, by the way was completed by a competent appraiser with 25 years of geographic competence).
So, the client must use the value conclusion reached by the AMC's New Jersey appraiser on a lake property in Wisconsin. The review that was completed didn't even attempt to comply with USPAP Standard Rule 3 and because the appraiser was from New Jersey, even violated state regulations (no reciprocity applied for).
I wish I had a better answer for you about how to deal with incompetent reviewers. Metamorphic, it's not you - they really are incompetent and it is demeaning to have to answer to someone who doesn't really understand appraisal.
You really can't fight it other than to find better clients. They are certainly out there. Turning down assignments is a drag but it's worth it in the long run.