I've been at this for a very long time too, 36 years of RC with another 10 of U-control before than. Most trainers have the tank too low for a good needle setting, so one needs to set richer than what you would if the tank was in the correct positon. I see far more sport fliers cook their engines than I ever see operate them correctly. Most instructors are clueless too, since they only do what they were taught.

You might re-read where I was talking about IDLE and the effects of varish. Plus, from some of the posts here, some are beginners for a very long time.