Well, I was taught how to fly by a Pattern Pro. He taught me that every time I change the throttle setting, a minor trim is usually necessary for straight and level flight. So, that's what I do. After practice, if you do a maneuver that requires a throttle change ( as most do ), You do the maneuver with the throttle change, then once finished, you get back to straight and level flight at the previously set throttle setting. It becomes automatic after a while, you just learn where to set the throttle after the trim setting and then fly. If you add or reduce throttle, to get straight and level, you adjust trim accordingly.

CGr