I have learned more teaching than I have any other way. When I am teaching someone a technique, they often ask questions I don't have immediate answers for. Maybe they ask where I place a hand or something, one of the small details that you just do without realizing it. I am forced to examine my techniques and thus get a better understanding of them. Also, if I show my training partners what I am doing, it makes it harder for me to do it next time, forcing me to raise my game.
When it comes to drills or learning new techniques with a partner, I am very vocal as well. I help my partner with details that he is missing and he helps me. If neither of us can answer the question, we call the instuctor or a senoir student over for help. IMO that is the best way to do it for student that have been long enough to know the difference between a properly applied technique and a fucked up tangle.