How can you think clearly when someone is watching and judging you? The ideal scenario would be - give a problem, leave the room, and come back after 15 minute

How can you think clearly when someone is watching and judging you? The ideal scenario would be - give a problem, leave the room, and come back after 15 minutes - give the candidate some breathing room.. to make mistakes, to try out few methods, to collect their thoughts. This concept of 'We want you to think aloud, We want to see your approach', doesn't match reality. In reality, the only time that happens is when both parties are trying to figure out a solution collaboratively. Not when one party already knows the answer and is 'testing' the other party. An author's first draft, or a speaker's demo, has a million corrections before it gets to print/stage. Can RR Martin write freely if the NYTimes reviewed his every draft version ? Can Steve Jobs go on stage and give a demo if he has not already rehearsed the entire saga ? It's like judging a person at their vulnerable stage. Unless they are a saint who can completely block out the existence of another human being sitting a few feet away, it's hard to concentrate. You're more worried about how your thought process looks than you are about solving the problem at hand.