I've read several people mention placing their kilt pins within hands reach, so they can verify it hasn't fallen off. I don't have a kilt pin yet, so maybe it's obvious, but how are kilt pins falling off? Most of the ones I've seen enter the fabric from the top, and fasten at the bottom. It seems that even if the fastener twisted and unlocked itself, the kilt pin should still hold itself in place using its own weight. Is that not the case?

If this is a common issue, how many kilt pins have you personally lost?