I use my Series 4 watch all day, every day. The most battery juice I ever used in a day over the last year was around 35%. My Series 2 watch before it, I barely managed to use more than 15-20% in a full day.
Do you have a badly optimised app or something like that? I just don't understand the battery life complaints.
I don't use any extra apps on the watch, just the clock, messages and Apple Pay.