Why does the second hand of an automatic watch move more smoothly?
The second hand of an automatic watch often looks smoother because a mechanical movement performs several half-oscillations per second.
This means the second hand doesn't just move once per second, but in several small steps.
Even so, the hand doesn't glide completely smoothly. Even with an automatic watch, the movement consists of many small impulses.
This behaviour is normal and is part of how an automatic watch works mechanically.