Wait, is this really about the rule or just proving your professor wrong? Sometimes things sell because they're different, not because they broke a design rule. Maybe your collection was just an exception.

That's a really good point about the biscuits. Sometimes those old recipes were written for ingredients that acted differently, like lard or a specific brand of flour. My grandma's cookie dough always needed a bit more egg than the card said because her chickens laid smaller eggs. You kinda have to play around with the liquids until the dough looks and feels right.

Wait, hold on. @dakotaknight, a carbide wheel is fine, but that "one firm pass" advice is risky on tempered. You still need that light touch. The real trick is the cutter pressure, not the number of passes. Pushing too firm on any cutter will shock the surface and cause a bad break. Your guy was half right about not going back over it, though. Never re-score a line on tempered, it just wrecks the tension.