4 stages - HR, then hiring mgr, then presentation & competency based q's, then finally a technical interogation.
First 3 stages were great - very professional. I was really interested in the role and from each meeting it seemed i had a strong chance of ultimately receiving an offer.
4th interview with new people was really unpleasant - purpose of this 4th stage wasn't explained and then without any introduction i was aggressively asked about technical processes and systems that shouldn't have been hugely relevant to the role applied for.
If detailed experience of specific technical tools was essential it should have covered in the job ad or interview 1 so that either party could have stopped the process then.
After interview 1 I spent approx 30-40 hours on research, interview prep, presentation prep and the interviews themselves. All of this was unnecessary as i had no prospect of getting the role because i didn't have (or want to have) detailed technical knowledge.