How do mechanical (automatic) watches keep time exactly when springs exert different amounts of force depending on how tightly wound they are?

Question

I know that mechanical watches have a spring that they wind to store energy, and un-winding the spring produces energy for the watch. But a spring produces a lot of force when it’s very tightly wound, and very little when it’s almost completely un-wound. So how does the watch even that out with high precision?

In: 95

Answer 1

In addition to all the answers here, it’s important to note that most mechanical watches do not keep perfect time. They have to be adjusted as frequently as every few months or as infrequently as once a year.

But the owner doesn’t notice because you have to reset the watch at the end of every month that has less than 31 days.