My point was simply that the rudder is not used for turning. It is used to control the yaw axis. With all of the aerodynamic forces that come into play, to move your rudder and expect your plane to simply do a flat turn without any other movement (IE pitching or rolling) is practically unthinkable. And to try to couple other surfaces into the equation IMHO is just plane silly. You would be much better off learning to fly the plane correctly. What do I mean by that? Let's look at a similar type of question.

"Every time I bank my plane with the ailerons, the nose pitches slightly down. Should I couple up elevator into my ailerons to keep the plane flying level?"

Well, by doing that, the plane would not nose down as much, but the amount will vary depending on the weather conditions, speed, etc. And if you DO make this adjustment, what is going to happen when you try to do a roll? Do you say, "When I do a roll, the plane has a tendency to snap because of the elevator coupling. Should I uncouple the elevators for doing rolls?"

Flying an airplane means just that. FLYING it. Making it go in the direction you want it to go. If you couple your elevator to the rudder for flat turns, and then you do a knife-edge, the coupling might work against you. If you couple your rudder to your ailerons for coordinated turns, the rudder will work against you if you try to do a side-slip on landing.

The bottom line is simple. Learn to fly your plane so you can make it do what YOU want it to do WHEN you want it to do it. Do the "coupling" with your fingers instead of your transmitter. Too many people want to use the brain in their transmitters instead of the one in their head. Believe me, the one in your head it a billion times better. But you have to use it.