So... is your comment orthogonal to mine? Ahha - yeah - I think I started to reply and wandered off topic :) I think it was more in reply to the OP's original

So... is your comment orthogonal to mine? Ahha - yeah - I think I started to reply and wandered off topic :) I think it was more in reply to the OP's original comment about puzzles being a waste of time. I think 8 hours is fine - if it's progressing in the right areas. I tend not to like panel interviews, but a broad range of interviewers isn't a bad idea - the best interviews I've had usually include walking the floor a bit, seeing the environment, chatting to potential teammates - although I'd worry that it would be hard to get a consensus if too many people are involved.