Battery operated clock movements (or clock mechanisms) are truly a modern marvel. These “little black boxes” can easily last 15 or 20 years with normal indoor use, and they are accurate to within a few minutes a year. Normally they will operate for a couple of years on a good, fresh alkaline battery.
The truth is though, that there is a huge difference in quality between a cheap imported movement made in a third world country in factory with a dirt floor, a one made in a clean modern factory with a robotic production line. No one makes a better battery operated quartz movement than a robot.