That was one advantage of moving through free-flight to control-line to gliders and eventual powered R/C. I remember when "proportional" was still a big enough step that radio manufacturers touted it in their ads. (The servos moves proportionally to the stick movement). The basics haven't changed. First you get the airframe squared up, then you get the controls trimmed, then you tweak.

I'm as guilty as anyone now in that I get "close-enough" and pull an end-point in to stop a servo binding at full throw instead of adjusting a rod's length. I center the servos (radio on) at 100% sub-trim, form and install the control rods, and then digitally trim. And I confess I love the ability to temper wild throws with adjustable exponential near the centered range to "smooth out" an extremely sensitive model.

As I fly and make any trim adjustments I bench the model after I'm back home and make the mechanical adjustments; eventually getting the digital trims minimized. I NEVER leave a trim switch/button (the ones on the radio face) so that I have to fly a model with those off center. The throttle is the only exception, and even then I like the trim centered and a seperate idle-down and kill assigned to switches. Back when trims were sliders instead of only display bars it was foolish and dangerous (to the model) to rely on something so easily bumped out of position.

As daRock says: any throw over 100% in the transmitter's setup is probably just a sign of a bad mechanical set-up and you're fooling only yourself. Those kind of adjustments get the extra throw in one direction by robbing the opposite end of the range or reducing servo sensitivity.