I'm wary of pushing people to move on to something else because I know that if I was on the receiving end, I would think that I fucked up and the interviewer is

I'm wary of pushing people to move on to something else because I know that if I was on the receiving end, I would think that I fucked up and the interviewer is trying to get the interview done early. A candidate who spends far too long on a part of the problem without getting anywhere will get some guidance and nudging. If they take that on board and get back on track then that's great - they're responding to feedback and correcting course. If they remain too committed to their chosen approach and continue to struggle, then we've seen it with our own eyes. At the end of the day, we're giving candidates the benefit of the doubt and recognising that, a lot of the time, it's their nerves that are doing the talking and you need to work with that.