Briefing is a waste of time. Take notes in the margins of your books so you can easily find information if you are called on in class. Briefing doesn't help- it is the outline that you need to spend your time on.
Well 3 days into school I'm not going to stop listening to the advice of all my professors to continue to do briefs. At least right now it helps me organize the case in my mind and helps me remember things.