If your plane requires a lot of trim to remain straight & level then it needs to be adjusted mechanically (adjust clevis) once back on the ground. Ideally the trims should be approximately centered with the plane flying straight & level. This way you will know the trims are set right (approximately) during your pre-flight check. If one plane needs full right aileron trim and the next plane needs full left trim and the third plane is happy with the ail trim centered but needs full down trim, how are you going to remember all of these? This applies mostly to radios with mechanical trims as they can be easily bumped out of position. Radios with electronic trim and "model memories" will typically "remember" trim settings when you go from one model to the next.