Yeah, and it's not just about the wrong fit, it's that feeling when the key starts to slip and you just lean into it harder instead of stopping. That's the exact moment you ruin the bolt. @christopher_wells4 is totally right, it's a basic feel thing you have to learn. I bet half the problem is people using those awful multi-tools with the bendy arms that let you crank at a bad angle. A proper set of fixed hex keys would stop so much of this before it even starts.

Honestly, weekly sharpening is fine if you know how to use a steel.