I can give you a good example of what you are talking about.

When assembling my Alpha 60 I needed to reverse the throttle servo. I took a look at the manual, saw a reference to "throttle reverse" and adjusted the radio per the instructions. As a result, when I got to the field to have the plane checked and maidened the throttle trim and throttle cut-off would not work. It took someone with decent knowledge of Futaba radios to un-do this and show me how to choose a specific servo and reverse it, for that model only. I don't know if I would have ever figured out why I couldn't kill my engine or adjust throttle trim without his help.

I too can fly my G4 simulator with ease on most of the planes, and land 'em. Big differrence between the PT-40 and the P51 in terms of throttle requirements on final. Even so, I welcome the assistance of our instructors. You never know when you might learn something.