I have found most of the things that give me trouble are not accessible if using an impact driver, either pneumatic or electric.
If you are in familiar territory (not moved in awhile), you can draw on people who buck the trends of the time. I once had a car painted at a small, used car lot that did their own work, with good results. Same with changing a steering rack.
The guys who buy at the auction, then repair them to sell, learn a lot of good methods in repair, and usually have good diagnostic abilities, as they pay a heavy price when they are wrong. Unlike a mechanic, or his apprentice on salary.
And yes, the guy with the lowest labor rate is not always the lowest price when the job is done. When I get something done on a fixed price job, I ask for the number to put on the cheque, with all the taxes and sundries in; if you don't, then every job is a cost plus affair.