Brick & mortar establishments have a reputation they have to maintain, and always being referred to as a good garage comes from satisfied customers telling their friends. This is how the shop EARNS BUSINESS. If it was a lousy shop then he would have no customers and no shop can afford to operate at a loss for long.
. If his shop is buzzing with many cars waiting for service, then obviously his name has gotten around....which is much better than the guy who has NO CUSTOMERS. Business is dead.
You actually WANT to stand in a line up.
It won't be for long. As not everyone has a difficult problem and the shop on average has 4 mechanics working on various vehicles at the same time. So, you won't have to wait long.
You can walk up to the shop and describe your problem.eg(loud exhaust, bad brakes, overheating, electrical problem, steering problem,etc. for the mechanics sometimes JUMP the order because yours is a FAST FIX. They get paid by the number of vehicles that get repaired....or may tell you "We don't do that type of work" but we know of a good shop who does do it and refer you to go there. So you don't just sit in line for nothing. A good shop knows what they can do and what they can't do quickly. You are looking for speed as well as a good job done. So are they. That keeps their reputation in the GOOD for longer.