I think in the main that most shops arnt out to rip or do unnecessary work, I have work at a place like that and I well lets say didn't stay long as I left. The place had a bad name and since had a name change.
Its not good for business really it takes a lot of time to do a cly change and if your aircraft is at the back of the hangar awaiting parts its taking up space that something else may be good be used for.
This idea that LAME wont to spend al your cash replace parts cause we is really not true.
cheers