Optional, as in "does not have a significant impact on the interview, i.e. not a binary hire/no hire issue." Interviews are, from my experience, stressful for

Optional, as in "does not have a significant impact on the interview, i.e. not a binary hire/no hire issue." Interviews are, from my experience, stressful for both sides, at least at the beginning: we have used this simple task as a way to get a conversation going. If, on the other hand, we had met a candidate who would insist that we're doing this just to stress them and that everything is a trap, we would probably be worried that meeting an actual problem on the job might be too much strain on their nerves.