If you learn how to use rudder properly in normal phases of flight (coordinating your turns, to start with), it will not be a problem on approach/landing. If there is a crosswind, I use ailerons to correct drift, and rudder to keep the plane pointed down the runway. This will result in touching down first on the upwind wheel, followed by the downwind wheel, and finally the nosewheel (or tailwheel). It works with a real airplane, and it works with our models.

*IF* you use ailerons and don't touch rudder, you will end up making a steady heading change into the wind, which will result in going off-course, naturally. If you "correct" this only with ailerons, you will end up wings-level and NOT pointed down the runway (looks like a slip from the ground, but you are actually in coordinated flight). You can get away with this with a lot of our light, tough models, but it's one reason you see guys at the field landing and immediately veering off the runway, or having other directional control problems on the ground.

If there is no wind, I still find myself adjusting my course and heading with rudder and aileron, mainly to keep the nose pointed straight ahead when making slight bank angle corrections. The rudder is also handy for quick, small corrections. Now, if you try to use ailerons for all corrections (especially heading corrections) and the rudder as an afterthought, you will find it's hard to correct quick enough, and then not over-correct. This is because using roll exclusively takes more time than just easing into the rudder a bit. With ailerons, you need time both to initiate the bank, and to get back to wings-level. Plus you will still be getting on the rudder to keep the plane coordinated (at least, you should). I find it best to correct drift with ailerons, and adjust heading with rudder (basically).

In the real planes, I also find myself making a lot of small, quick corrections with rudder and aileron on approach. It's more intense and precise than RC, probably because I have a better view of my approach course and heading in the real plane (slip indicator, runway centerline, seat of the pants, etc). As I do not fly paying passengers (pleasure and personal transportation only), I don't have to much worry about passenger comfort on approach/avoiding side loads, so on final approach, I focus on correcting drift and pointing straight down the runway. Again, I tend to use ailerons to initiate drift corrections, and rudder to keep the plane pointed the right way.

On takeoff, you really don't want to try to use rudder into the wind, as some have suggested. Reason #1: in this phase of flight, you are at high power, low speed, and high angle-of-attack. Any deviation from coordinated flight will reduce lift on one wing, and increase chances of a stall/spin. It's true that if you are rolling straight along the runway with a crosswind, you are basically in a slip. However, as soon as you lift off, the aircraft will begin to weathervane into the wind AND begin to drift in the direction of wind. Typically, I find the plane stabilizes in the air pretty quickly on takeoff: weathervaning is very slight (if even detectable at all), the plane starts drifting in the direction of the crosswind pretty quickly. So, I focus on keeping the ball centered. If you really want to stay on a course straight off the end of the runway, simply turn into the wind (a normal, coordinated turn) until you have a crab angle that puts you on the ground track you desire. There is no reason whatsoever to put the plane into uncoordinated flight just so you can point the nose on the same heading as the departure runway, and using rudder into-the-wind to correct drift is basically the same as making a rudder-only turn (no good reason to do it, except for your own amusement).

With my RC heli, I REALLY notice the effect of bank angle and yaw angle...I can see very clearly when I need to roll for drift correction, and when I need yaw to correct my heading. Everything related to coordinated flight and "rudder" use is amplified with helis. Fixed-wing planes let us cheat on a lot of stuff.

Matt