What clock face are you using? Those can have quite a big effect - for instance Slope Clock which updates once a minute still uses quite a bit of power because it's animated.
GPS is a massive power draw, so yes, if you have it on the battery will flatten quickly - there's not really a way around that.
So to get the absolute best battery life, you want:
A non-animated clock that updates once a minute
'Wake on twist' turned off
Ideally no (or 10 minute) heart rate sensing
I have a bunch of watches here that I use for development, and for the ones sitting on the desk (especially if they just have the factory apps on) I reckon I must get almost 2 months
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
What clock face are you using? Those can have quite a big effect - for instance Slope Clock which updates once a minute still uses quite a bit of power because it's animated.
In order of power consumption (there are some figures at https://www.espruino.com/Bangle.js2#power-consumption):
GPS is a massive power draw, so yes, if you have it on the battery will flatten quickly - there's not really a way around that.
So to get the absolute best battery life, you want:
I have a bunch of watches here that I use for development, and for the ones sitting on the desk (especially if they just have the factory apps on) I reckon I must get almost 2 months