Just for clarification- I wasn't trying to be funny. The better the player the more variations I would allow. That's why I wanted him to let us know his handicap, etc. No sense changing Lee Trevino's arched left wrist at the top- if he's got a pattern that works well.
Now, it's just me but if the same player had a Lee Trevino looking swing but was a 40 handicap - then I would try to make it more conventional- simpler. Likewise, I'd be a little nervous or careful about changing a component in Lee Trevino's swing- I'd rather have him understand the components in his swing and realize where things might go wrong- or how all the components add up or offset to produce good golf shots.
So it's a combination of how well the pattern's ingrained and how proficient the pattern is - that would determine if you want to change it- ofcourse, combined with the goal of the student.
Great points Mike. This is where the Artist part of being an instructor comes in. You must know what to 'fix' and what not to fix, and there are no fixed rules.