The veteran and the beginner can make the same move for completely different reasons.

The same move can come from calculation or from instinct. A beginner may stumble onto what an expert chooses deliberately, and the outcome is identical while the understanding behind it is not. Judging comprehension by results alone will mislead you in both directions.

This matters when you teach and when you learn. If someone gets the right answer, ask how they got there before assuming they know. And when you get something right by accident, notice it rather than banking it as competence, since the accidental version will not be available when conditions change even slightly.