I had one first call with the recruiter (around 20 minutes), then 2 Skype technical interviews (around 45 minutes each), then 3 on-site interviews in London (technical, around 1h each), and finally 2 technical Skype interviews with people in Palo Alto (around 1h+ each). Yes, that's 8 interviews. People were nice, problems were interesting, and the recruiter did a good job organizing everything. They finally told me they really liked me but my motivations were not perfectly aligned with the job itself, a bit frustrating but understandable.