Wowza... What a variety of use time...
I get 2 days, but charge every morning (always seems to be at 50-60%)
I have a dark background but WiFi on, location on, NFC off, AOD off, auto brightness on, auto bedtime mode overnight, sleep tracking but not snore or co2, 10min heart rate not continuous.
One long walk each day which is auto tracked, hundreds of notifications, occasional call on it, daily health checks...
I bet AOD and how light/dark the background makes a big difference along with how regularly it checks health stats