Learn about battery service and recycling for Apple devices. All rechargeable batteries need to be serviced eventually.
www.apple.com
From the above link
Apple Watch Owners
Your battery is designed to retain up to 80% of its original capacity at 1000 complete charge cycles. The one-year warranty (for Apple Watch and Apple Watch Sport) and two-year warranty (for Apple Watch Edition) include service coverage for a defective battery. If it is out of warranty, Apple offers a
battery service. Prices and terms may vary.
I find that very optimistic. My watch was about 2 years and 4 months when the battery health went down to 78%. and as you correctly assumed, i would charge my watch every other day or day and half initially, so my cycle count could at best be 500, perhaps 600 after 2 years and 4 months. That is far from the designated 1000 cycles. If my watch was let's say 900, I would be fine with that but seeing how my watch barely hit the half of the designated cycle count and the battery crapped out, I am not super pleased with that.