Yeah, the other 8 hours are when you're sleeping and the battery usage is relatively minuscule, given that it supposedly can last 72 hours in power reserve mode

Yeah, the other 8 hours are when you're sleeping and the battery usage is relatively minuscule, given that it supposedly can last 72 hours in power reserve mode. Eight hours of not checking time or anything probably doesn't have a more than a percent or two difference. It's safer to say 18 hours as all day rather than claim 24 hours and have people claim false advertisement when they try to push its for an extra 8 hours. I use my G watch R pretty frequently throughout the day (still at 84% after about 10 hours) and on days where I forget to plug the charging dock in at night, my battery isn't much lower once I wake up. I don't imagine it's much different with the Apple watch.