I've been using rudder for quite a while for slow rolls / rolling circles but just ailerons for turning until recently as I've started doing more and more 3D like harriers etc which yyou want it for and inverted flat turns look lovely.
The only thing is whereas I don't have to think about orientation with ailerons now I do have to think about it with rudder so I've started using it for all turns so it then becomes second nature over a peiod of time BUT wished I started using it ages ago as I'd be there now and would make my 3D easier. I think generally the concensus is you don't ever HAVE to use rudder (except maybe on the ground) but if you do it makes you a better pilot in the long run.