The effects of thrust angle tend to be reduced with airspeed where the effects of a fixed amount of rudder tend to increase with airspeed. The prop is a shorter distance in front of the CG than the rudder is behind the CG so the rudder has a greater mechanical advantage to yaw the airframe. Rudder and thrust really have different functions so they should not be thought of as interchangeable. I know this is a way oversimplified explanation so please don't beat me up over it.

Many years ago, for both models and full scale, I was taught that "rudder always works" at any airspeed and that lesson has never failed me. We can build in thrust angles and we have rudder mixing on our radios and these are good but we always have to remember that the rudder stick always moves and works if we only will use it!