If it's not clear what I mean is this,
In the cub, if I trim for 65kts with zero power and then apply full power, I will not retain 65kts, the nose will pitch up way too much and the aircraft will slow down quite rapidly and no amount of waiting will bring it back to 65kts, it will wallow around the stall at 47-48kts I must push quite hard to keep the attitude to maintain 65kts and will consequently climb, I then trim to hold the attitude.
Trimming for an airspeed as such works for a boat load of aircraft though
There's no one method that works for everything but it all starts at the same place.
Power + Attitude = Performance, Select Hold Trim.