Tell me about a piece of work where one small error would have been genuinely expensive. What was different about how you worked?

Anyone can claim to be detail-oriented; this asks for the machinery. People who have really done precision work describe systems — second passes, checklists, ways of catching their own fatigue — while everyone else describes a personality trait.

• What kind of error worried you most?
• Walk me through your checking method, concretely.
• Tell me about a mistake the checks caught.
• What did the extra care cost?

The specific failure modes named and guarded against, a repeatable checking method rather than generalized carefulness, at least one catch story that proves the method worked, and honesty about what the rigor cost in time.

"I'm a perfectionist" with no method attached, checking that amounts to reading it again harder, stakes inflated on an ordinary task to fit the question, or a zero-defect record with no catch stories at all.