FDIC uses structured interviews, typically with four questions, each of which has subparts to them. It is critical that one writes the questions down to ensure you answer each subpart, always using situation, action you took and positive outcome of the action. They want an organized, full answer. They can not answer any questions, and because it is structured, it can seem very impersonal; however, it is conducted to ensure fairness and prevent lawsuits.
I had one interview which lasted an hour. We were given the questions in the waiting room approximately an hour before we were interviewed. Two people were there to interview each individual, one of which took notes while the other person asked the question.