I have an apple watch nike S3 cellular, my other half an S2 nike. We set off for a run together this morning, started at the same time. My 1 mile notification buzzed 2 seconds after hers, however her average mile per minute was showing 12 seconds more than mine. How does that happen since we ran side by side, started the same time on our watches, and the GPS tracked the mile mark on both watches within 2 seconds of each other?! By the end of the run my watch was showing total time as 20mins 11 seconds, hers 20mins 32 seconds. Just struggling to work out where these extra seconds are coming from- not important in so much as we're just running to get fitter, just baffled as to why they're different.