On-site PM interview: four interviews in a day. Second one was lunch interview; last one was with the manager of my previous three interviewers. The first two interviews of the day were very heavily behavioral (discuss your projects, tell me about yourself, are you competitive, why aren't you looking for a software engineering position, etc.). The last two were packed with design questions. First interview was neutral; not bad, not notably good. I think I did well on my second and third interviewers. I just happened to click very well with my second interviewer, and we actually got pretty off-topic just chatting about product design during lunch. My third interview was okay; I didn't get the answer "right" for one of my three design questions but he didn't seem to mind. I was completely exhausted at the end of the day and couldn't even answer the simple questions that my fourth interviewer asked me - simple questions that I had heard before! - and I even apologized to him about my poor performance. I guess they expected candidates to be worn out by the fourth round, though, because I actually met with the team's hiring manager after my third interview and he gave me his contact information.