There's nothing worse than being out of town and having your watch battery go dead, while your waiting for your flight. With a Rolex or other Swiss watch with a mechanical/automatic movement, there is no worry. Yes, it may be a second or two off, but they keep running. TV stations don't even start on the second like they used to. Before we could by atomic clocks cheap, I set my watch to a short wave radio. Not for 30-40 years. Maybe Mac people like that part. Their amps seem to keep on going too.