AW Series 6 44mm here, the battery life has been god awful for a while, but with 10.6.x it barely lasts 24h. The only major thing I actively use the watch for is tracking one workout, around 1h, and paying for stuff. I can see on the battery usage screen that my active usage is not the problem, the background usage is. I only have a couple of apps installed that is like seconds usage, have noise measurements off, background app refresh off.
Tried unpairing/pairing it, since setting it up is not that much of an hassle for me, nothing changed. Mostly indoors for my typical work day, gets to the end of 24h always on the red now. When outdoors, it struggles to get through the day, and died on me in a couple of occasions.
Battery health is 86%, it was replaced through battery service not even 1 year and a half ago.