(I'm talking from own sad experience here.) When you start to work with real demanding pieces, maybe for hours every day, you will be in deep trouble if you are doing it wrong. You learn the basics in your first lesson and then you play on and on for years, until you start to get hurt. My own teacher is very interested in ergonomics, but truth is that it is rather often neglected. I think I will post the link to the instruction videos on the Student's Corner as well, because the material is rather unique.