To me it depends on the type of plane and how I want to fly. If it is an aerobatic plane with a symmetrical wing, I trim the elevator at full throttle, trying to find a setting where the plane behaves the same upright and inverted (assuming the CG is correct). If I fly "right side up" most of the time, I trim the airplane to fly hands off at the speed I want. Some people prefer to fly landing approach with a little backpressure on the elevator, others like to adjust the trim for a nice approach speed with the stick in neutral. Do what feels right to you. There is no right or wrong, just personal preference . Your transmitter, your rules. Experiment and have fun.