Depends on the plane. Jets were not specified, nor were model planes, but I guess that's what was intended from the forum title. Some posters seem to have gone on to full size discussion.

Full size prop aircraft use rudder all the time to coordinate turns.

On full size jet transports (I flew 747, 757, 767, L1011, HS Trident) the rudder is used during take off, remove drift on landing, and in the event of engine failure. Unless an engine fails they are just foot rests.
Jet fighters may be different, I'll let the military pilots speak for themselves.

Flying models, I use rudder on take off, knife edge, spin, stall turn type manoeuvres and that's about all. I don't think balancing tuns is relevant on jets (or fast aerobatic prop planes).