Simple harmonic motion - Its resonant period makes it resistant to changes from perturbing forces, which is what makes it a good timekeeping device.

mechanical watches (spring loaded watch) are less accurate, often with errors of seconds per day, and they are sensitive to position, temperature, and magnetism.

Mechanical movements use an escapement mechanism to control and limit the unwinding and winding parts of a spring, converting what would otherwise be a simple unwinding into a controlled and periodic energy release