I went through my university's campus recruiting process. Once I was told I was accepted to interview, they held an evening event the day before the interview to explain the case study process. It was incredibly helpful and I got a chance to network even before the whole process began. I highly recommend going if possible. The first interview was a 30 min behavioral followed by a 30 min case study. My interviewer and I got very off topic in the behavioral so we didn't get to many of the questions. The case was much more difficult than what we had practiced, which may be because I have a very math/finance heavy background with little operations knowledge. It was based around how to best integrate an ERP system to a company looking to become more efficient across its 30 offices. My interviewer was very serious and gave me zero signs of how I was doing -don't let that throw you, some interviewers like to do the "bad cop" style-. I got called back to a second interview the next day which was another 30 min case study. This time is was more focused on systems development life cycle.