I don't think it's necessarily taking the mick at all - like you say, plenty of people who say they can do X, Y & Z, then turn up and don't have a clue. By all means have one interview with a general HR bod to see if they'll be a general fit for the company, get them to do a filter competency test, and if they pass that then a "proper" interview with the team they'll be working with (saves wasting the time of the higher ups on useless candidates), but I'd draw the line at 3-4+ interview stages, you should have more than enough info to make the decision after that second interview!