OK so I've read that a previous version 8.35 I think was held back for battery life issues. I got my watch about 2-2.5 weeks ago and it's been going great. There was one firmware update in that time that was no problem. I had 12 days of battery left on my watch at the time 8.37 was installed and the next day the watch was telling me 6 days.
So this thread I started because I wanted to know if anyone else has experienced this.
No I didn't change anything on the watch and no I don't use watch faces with extra data requirements.
I will wait and see anyway, how many days it goes back to once I have to charge it again in 6 days or so.
Hopefully it's all just a weird co-incidence.