I went through two separate interview rounds on site a year apart since I turned down the initial offer and then it was resubmitted to me a year later when I was ready to commit. My process included several phone conversations with key people and an initial HR screening. A project assignment that I presented in person on site as well as a half days worth of interviews after the presentation. The follow up involved a phone call from the manager and then another round of in person interviews with some of the same people and a few others onsite. The major 'wild card' after the interview process was clearly the manager who asked me NO questions and seemed to not be able to answer a single one of my questions about workload or process. It should have been a major red flag but the rest of the opportunity was so good that I ignored it.