I mean some "repair" shops have to cover the extra time needed while the "mechanic" has to keep guessing, and replaces part after part after part until somehow he stumbles across what is actually broken.
Red Hot technicians are loners. They do not want anyone around them especially not supervisors trying to tell them what's wrong. When I passed a few months in college working for an auto dealership as a line mechanic (electrical) I threw a fit because the service order writers had the guts to write repair functions on the repair order. I marched out to the service island, chewed their ass out and yelled YOU WRITE DOWN THE SYMPTOMS NOT SOME HALF (baked) DIAGNOSIS on the work order. This lead to a confrontation with an idiot service manager "The International Harvester Travelall with the A-727 Mopar transmission has the neutral safety switch on the steering column and not on the rear end of the manual selector rod in the transmission".
I flipped 5 100 dollar bills on the service writer's desk and said "Put your money where your mouth is". He didn't like the idea of having a half dozen other mechanics witness this. Needless to say this greatly assisted my later decision not to work in a "corporate" environment. "Teamwork" many times is translated to "Subservient To Stupid Management".
Kudos to the OP's intelligence and willingness to go the extra mile and find competent technical ability. Good technicians are efficient and do not need to cheat.