Well lets say that if a medium to large lender is my client, rather than an AMC, they are more likely to ask. I really only do work for AMCs when the market is hot and they accept my higher price of maybe $700-$1600 for an SFR. And, - AMCs just want a rubber stamp that gets by automated checking. Right now I have not reapplied to the AMCs I worked 2020-2022. I still get occasional requests from a few old ones, but I know they are not going to pay $750+ for an SFR appraisal. So, I don't bother with them.
I have plenty of things to do now without taking on more appraisals. But, yes, I will do estate appraisals - maybe. Programming takes most of my time.
I really DO NOT understand why you are concerned by such a percentage. You should always assume that every appraisal could wind up in some spotlight and worst could come to worst. IMO.
Maybe what you are really after is an assessment of problems should YOU start doing more advanced appraisals. You should be worried. It is one thing to dump a MARS model into a report and another to be able to explain it in reasonable terms. You have to be careful with that. You could fall into a dangerous predicament if your appraisal gets caught up in legal proceedings whether or not it is your fault - and you really cannot explain or defend parts and pieces of your model. If you make latitude/longitude adjustments - you will have to have a good understanding of statistics and the market to answer questions as to how that could possibly work - I need to write an article on that - but haven't got around to it yet. [And how does that work? - Good question.]