Similar experience here. I have a Series 4, and charge it on an evening when I'm not doing much for about 30/40 mins and it's good for another 24 hours. The new sleep tracking feature asks for 30% battery life before being enabled, and lets you know in advance if you need to charge. Before Apple added that feature to the OS I was using the Pillow app and that would happily blow through 80% of the battery in a night.

Overall the device has been a massive net positive for my health, I really love it.