I've never gotten any real pressure from an agent to hit a value or select certain comps. But I've gotten extreme pressure from many BPO companies to do so.
I think the mill doesn't want to have egg on their face. They get pressure from the bank to show a sense of consistency. While appraising 101 has the philosophy of never having a predetermined value of a home, mills and banks alike have a tendency to throw that out the window. Not to mention if a mill has too many discrepancy reports, that could cause two problems.
The first is the mill's reconciler will have too much work on their hands, and secondly the excessive inconsistency could cause the mill to loose a customer or two. So the onus is placed back on the BPO agent to alleviate either circumstance I feel.
Someone on here (I don't remember who) said it best a few months ago. They said that the mills often want us to put a square peg into a round hole. In a picture perfect world we could do that, but we obviously don't live in such a place.
My $0.02