One other thing to think about is wind. Yes wind. On a clear day with a steady breeze, flying up and down the field with the wind traveling crass-wise, you may tend to trim into the wind. When you turn around, you start trimming the other way. At some point you just leave it alone and handle it the way it is. But you never know where it really should be unless it's dead still.

True, hard landings or a good chunk of sod will compress the springs in your servo-saver, and trimming while taxing may straiten it out, it will throw your rudder. When in the air, you notice the plane leaning to one side, so you trim ailerons (because you tent to think the the rudder is fine, but mostly you don't want to change the steering). So as you truck along with a smile on your face thinking that your plane is now trimmed, when in fact your control surfaces are fighting each other. You can tell this is happening when you fly slowly above in a strait line... the tail wiggles and slides a bit as it coasts along.

To me, a strait ground behavior is paramount.