Thought I'd add one more thing.... if you get invited to a case prep session with MBB or whomever, show up prepared. These are often done in groups of 3 or 4 people with 1 consultant where you all get to work through the case together. I've been to some where the 3 or 4 students are fairly on par, and things move with reasonable speed and no one looks like an idiot. I've also been to some where people had clearly not prepared at all - and their excuse was "its non evaluative, so I figured I didn't need to prep":
1) Nothing is non-evaluative. You ever meet someone and NOT form an opinion? You really think that if a partner is impressed they wont take note of who impressed them?
2) Bombing a case in a private room and one partner is painful. Bombing it with a partner and two or three classmates is embarrassing
and painful.
3) It wastes the time you have - you don't get meaningful feedback because you need so much more work that all you'll likely hear is 'Keep practicing', rather than specific tailored feedback.
4) It makes it frustrating for the others who have clearly prepared.