Battery draining issue has been solved with my Apple Watch series 5 44mm and my wife’s Apple Watch series 5 40mm ....
Heres what I have done to solve the issue
1 Set both Apple Watch and iPhone back up as new devices
2 in the process of setting both the Apple Watch and iPhone, decline sending info to Apple and App developers, also decline turning on location services .
3 Turn off all push email notifications and turn it to manual only
both myself and my wife have been seeing a huge difference in battery life ... I’m taking my watch off charge around midnight and I still have (at it’s worst) 97% around 7am and by midnight I’m getting (at its worst) 75% remaining and that’s using the watch in low to med usage
this is day 9 and everyday I’ve been getting very similar results (my wife’s 40mm is getting very similar results over the period of time also)
also I’ve done a test over 48hrs without charging the watch and at the end of the 48hrs I’ve still had 39% left which is a massive improvement over the just 8hrs with the battery issue, before I did what I done.
Yes it’s a pain When you have to manually get emails and use maps and weather (from the phone as not tried it on the watch ) but just having that nice battery life makes everything worth it
3 of my colleagues are also testing my possible solution to the battery drain with their Apple watches and since I’ve told them about what to do, they all have been getting the exactly the same results over the last 5 days as we are, so this all looks promising in this terrible issue
Hope this helps ;)