The sad truth is above it right, it costs the appraiser money. The worst is that the supervisor takes on far more liability than the trainee. Here is how that works. Say after a few months the super decides the trainee is good enough to inspect by themselves, do Page 1 correctly, and muddle thru page 2 semi-adequately. So they don't review the work as thoroughly as they COULD (not necessarily as thoroughly as they SHOULD)...
The trainee decides they are not making a lot and starts seeking short cuts. So the client asks for a cost approach. The trainee decides that they know "about" what the replacement cost is say... $143.15...just PFA (pulled from a...ir) and they think the lot ought to be worth say $75,000. But they don't really search the land values and just make up some numbers for "support". And they make a stab at the effective age...making sure that any shortfall is covered by "site improvements" so that the Cost App is semi-close but not exactly the same as the sale price. Super glances over the numbers and they seem "reasonable."
Then a reviewer comes along and actually checks those land sales. Can't find them in the public record so hunts up the closest land sales and learns that the most recent lot sales were $100,000, $129,000 and $114,000... so he digs deeper and using the referenced "cost book" finds the RCN way off. So looks closely at the comps and find they are not real close and there are more sales closer. The report goes to the board. What happens?
The board calls in both the super and the trainee who agrees his work was sloppy. He/she gets a hand slap. Probation and take a couple basic classes (which likely count for CE at least.) The supervisor? They get their license ****canned, they are banned from supervising anyone, have to take the full 2 day USPAP course over, and are fined $1,000 plus investigator costs of $2,300. They are on probation for six months and have to submit a monthly log and samples as demanded. Now your next bill for E & O is doubled. You will never testify in court without being reminded of the infraction, and you have to truthfully tell any would be AMC client, if they ask, if you have been sanctioned. That nailed at least 2 former forumites in Oklahoma.
There is no up side for the supervisor.