In gliders you'll find that a tiny bit of pro-turn rudder is needed while maintaining the turn
I've always found the opposite actually (not arguing the point by the way!). Especially in something like a K8 in a steep turn I've always found a smidgen of top rudder and opposite aileron is needed to keep the string where it should be otherwise it just slips away. Might be something to do with the fact I'm built like a tank though and the cg is always way forward. Then again it might not.
Regarding instructors, I had three who were all excellent and all old timers relatively speaking. All ex mob flying instructors and sort of semi retired apart from one who flies for BA occasionally. Any good club will keep detailed records of each instructional flight and all the next instructor has to do is read up on what happend last time and which if any points need reinforcing.