Mentoring will always be what you make of it. At the very least, all it does it tell you who has done the requirements to unlock it.
For me I mostly didn't say much other than when I noticed big mistakes, or if I was asked questions.
For stuff like Ex primals, I refused to explain the entire fight start to finish, instead I encouraged people to research for themselves before trying (as this is what I feel should be normal behavior for going into Ex and higher fights). If people weren't listening or refused to watch a vid, I'd usually stay but vote abandon after a few wipes. Eventually, if it was really hopeless, I'd leave or go offline.
