That bit set probably matched a standard profile, not a worn one. Those old mills kept their cutters sharp and replaced them often. The real trick was finding the exact original profile they used.

Honestly @zara_sanchez calling it a "trick" feels harsh. That guide is just trying to make a living, and the stare is probably because he's had too many people take the whole tour and then just walk off. You know exactly what you're getting into with a free tour, it's a tip-based job. If you can't afford to tip, you should pick a paid one from the start.

My brain resets after a few hours, honestly.