Interesting topic. As a teacher and as a student, I think there's also something to be said for the concept of readiness. Sometimes a student simply isn't ready to learn something, no matter how well it is being explained. In my own skating, I know my coach told me certain things over and over, but it was as if I couldn't hear them until I was "ready". Then, one day, things would just click, I would express understanding, and she would look at me in amazement, saying "but I have been saying that to you every week for 6 months".
In my own teaching, as a clarinet teacher, I have done the same - taught the same concept over and over, saying the same thing different ways (the best teachers have many ways of explaining the same thing), getting no immediate results, but knowing I was preparing the ground for eventual understanding. Sometimes the student would go off to a camp or workshop and come home all excited, having discovered the thing I had been working on for months. Maybe the instructor there had said it in a slightly different way that turned the light on. Once, the student came back and excitedly told me what the camp instructor had said and it was EXACTLY THE SAME THING I had been saying for months. She just hadn't been ready to hear it yet. I just smiled and congratulated her.