I'm trying to get a stash going for when I go back to work. Yesterday I went to the Back to Work classes at the Breastfeeding center of Washington DC which was really helpful but got some information that seemed to conflict what I have read in books. I have read that you should limit pumping sessions to 10-15 minutes to prevent nipple trauma. At the class yesterday the instructor said you should pump until your breasts are empty in order to make more milk. What do you do/were taught?