when you say "they spent a lot of time" what does that mean exactly if you don't mind me asking? The reason I ask is that with my son a workout with his private QB coach will last an hour, and of course that is multiple times per week sometimes and you did say QB's are different which I agree with, they're unlike any other position, but I can't imagine anyone gets that sort of attention individually at any point.
What I noticed is they get more critique during film than they get in practice. Coaches get them into film and pick them apart.