I went through an agency. The process started by agency/click arranging an one hour-long skype interview with two C-level execs. This was mainly stuff like "why do you want to work for us, how long you want to stay, where do you see yourself in 5 years". After a successful skype-interview, I was invited to do an hour-long presentation+Q&A with the hiring manager & one of the directors from 1st round interview, followed by a 30 mins chat with HR - all questions re travel, working times, culture etc answered. The live interview was set 4 days after the phone call (with a weekend in between). HR sent me instructions on what to present (15 mins presentation expected) four days up-front and I was able to prepare just using the "about us" on their homepage.
Everyone was very nice and calm, I never had the feeling of being "tested" or scrutinized - it was a (surprisingly) pleasant experience. HR did email and call me before the live-interview to make sure I understand what's expected. Feedback was given within 24 hours on both interviews (so no sleepless weeks - just one nervous evening).