What makes a lock feel 'right'?

I’ve spent forty years turning tumblers, and I still can’t explain why some locks just… click. Not the mechanical kind—more like the moment the weight shifts, the resistance gives, and you know it’s done. Like the universe sighed. I keep thinking: is that feeling real, or just memory? Last week I found an old bank vault key in a drawer. Turned it once. Nothing happened. But I swear I felt it.