I did all four rounds and it took about 3 months. First was with a recruiter and he was nice. Then I did not hear back for a month so I thought I didn't get it and then I find out I made it through. Scheduling was difficult, but the same recruiter would schedule calls before each round and make sure I was prepared for the interview and it was great, I've never experienced that. The recruiter emphasized the importance of knowing the job description up, down, sideways, you name it, so I worked hard on that. I eventually did a case study and the final round was with a VP. I lived about 100 miles from the office, but I made the effort to drive there for 2 of the 4 rounds. After the 4th interview, I get a call from the recruiter saying they will not be offering me the position because I did not seem interested enough and that I did not know what the job was. I felt very led on because I always emphasized how I was very interested in the position and I at one point quoted part of the job description.