If you have LTE version you can turn mobile connexions OFF most of the time as long as you have your smartphone near.
Can also turn wifi OFF in the same situation since you're connected to the watch with BT, wifi is useless.
Turn ON these only when needed.
For my use btw 4 to 6 brightness is enough.
Despite notifications activated, with these settings i have over 1 day 13 hours left with always on display turned ON...