I just had my second case interview practice interview with a consultant from Mckinsey, and it was a major improvement from my first. I owe a lot to your Look Over My Shoulder® Program, it made solving the case a lot more natural.
I wanted to ask you regarding feedback after a case interview, since I will be doing several interviews back to back, is it appropriate to ask the interviewer for feedback at the end of the case, or should I just ask for his/her contact information and email them about it later?
It's great to hear about your progress on preparing for case interviews with Look Over My Shoulder®.
In terms of asking interviewers for feedback on how you did, it would be best to do it after the fact. First, they don't have much time.
Second, they probably don't want to tell you for a variety of reasons -- if its negative, they don't want to get into a confrontational conversation when they have another interview that needs to start in 100 seconds, or they don't want to negatively influence how you do on the next interview starting in a few minutes.
If it's a positive, they may not want to imply you made it to the next round until they have spoken with the other interviewers.
Also it tends to come across as a little awkward in the moment.
If you ask after the fact, the person has more time to tell you. The final decision has already been made, so they can answer more precisely. Some offices and some interviewers will give you feedback after the fact, even if you don't ask for it.
So they might say, "You pass this round, but you need to work on X for next round."
Note - not all interviewers will give you feedback, that's just a reality and not much you can do about it.