The Apple Watch battery life whilst using GPS is something like 5 or 6 hours, right? I don't know about a 245 but my Garmin watch does double that normally, and over a day in the less accurate ultratrac mode. And yes, I have required more than 5 hours on a few occasions. 5 hours is probably enough for most people most of the time but it's lacking compared to what a real sports watch can do and I personally wouldn't pay top money for Apple's half-arsed version.