Apple

I mean I charged my Series 6 either in the hour before bed or would just let it charge while on my way to work in the car. So usually I averaged about 45 minutes to an hour without it on and charging a day. It usually never got back up to 100% but it stayed within about 85% to 30% everyday with those habits. I now have an Ultra 2 and only charge it for about 45 minutes to an hour every other day.

While it would be great to having longer battery life like Polar or Garmin or Fitbit or other dedicated sports watches the battery life of the Apple Watch doesn't prevent you from using it for sleep tracking (which from my use will at most take 10% of battery if you had a pretty restless night of sleep).