My understanding is that the screen is still updating 60 times a minute. It’s 1 Hz, not 1/60 Hz. I don’t think taking advantage of that to change the screen vs changing it to the same thing (what’s happening right now) should be that detrimental.
It’s not that it would use additional battery. It’s that it would look … really, really weird. At least, on analog faces. (Digital seconds, like an old-style Casio, would be okay — but none of the Apple watch faces I’m aware of have such.)
I know what you’re thinking: lots of mechanical watches and clocks “tick” instead of “sweep,” so they instantly “update” the second hand.
But that’s not what’s actually happening.
Instead, the second hand is at rest most of the time, yes. But then it accelerates very rapidly, and immediately decelerates about as rapidly, coming to a stop at the next marker. Some even visibly “bounce” or “vibrate” for a brief moment. It’s like a drag race to get to the next stoplight, and then waiting for the light to change.
If a digital watch with an 1 Hz refresh rate tried to replicate that, you’d instead see the second hand “teleport” from one position to the next. It would be extremely unnatural-looking, solidly in the “uncanny valley.” Plus … we don’t know the total time to refresh the screen in this 1 Hz mode. Currently, almost nothing gets updated with each refresh. But suppose it takes a tenth of a second for the refresh to make it from the one side of the screen to the other; not at all hard to imagine. If you had to update more than a few adjacent pixels in such a system, the “jelly scroll” effect would be over-the-top bad.
I do expect that it won’t be all that many years before we go from “always-on” displays to “always-active” displays, where at most there’s a color scheme change when you lower your wrist (and maybe not even that).
But we’re not there yet.
b&