It's all stored on Strava. You just push a button when you start running and when you stop. If it's habit, you notice pretty fast if you don't have your phone, especially if you listen to music or something when you run.
I don't run as much, and never more than 1h, yet it happened several times to me that my phone battery died on me while running. (I'm obviously not carrying a powerbank with me, and my phone is many years old). It would also expect that Strava or the network would fail from time to time (no need to go as far as antarctica for that - I've been living in germany for less than a year and I have lost track already of how many times the 5G/4G network has been out of order for hours). I guess strava has a good networkless mode. Or maybe my experience with tech has been particularly bad and I'm an outlier?
I don't know about Strava, but I have a Garmin running watch. It's got a battery that lasts for over a week and stores all activities until it can be uploaded via phone. The only failure point there might be user error, but given we're talking about a 1 mile run, I barely count that as penance if I have to redo it.
The battery life of Garmin watches is astonishing. When I get a low battery alert, I still have several days to plug it in. If my phone dies, my watch stores my run until I get home, at which point it logs into my Wi-Fi network and uploads it automatically.
I had a bunch of Fitbits over the course of a decade and wish I'd made the change earlier.
