S1: A $6 R1 competitor?

As one with teaching experience, the idea of asking a student "are you sure about that?" is to get them to think more deeply rather than just blurting a response. It doesn't always work, but it generally does.

It works because the question itself is a hint born of knowledge. “Are you sure about that” is a polite way to say “that answer is wrong, try again”. Students know that, so instead of doubling down will redo their work with the assumption they made a mistake. It is much rarer to ask the question when the answer is correct, and in fact doing so is likely to upset the learner because they had to redo the work for no reason.

If you want a true comparison, start asking that question every time and then compare. My hypothesis is students would start ignoring the prompt and answering “yes” every time to get on with it.