I'm keeping my Xs MAX at least until 2021. Going to try to go for 2+ years for the first time with this iPhone. I find that I'm using my iPad and MBP a lot more these days, vs my iPhone --- unlike the last 3-4 years where I used my iPhone a lot more.
My XS Max battery is still almost 300 mAh over design capacity - even after almost a year of usage.
But I'm getting old ... kinda tired of always getting the latest and greatest - my bank account will thank me too after this Xs Max (Apple Upgrade Plan - so not as painful).
Same for me I bought the max because it’s got enough oomph to last at least two years. There’s nothing taxing this phone right now, I’m really happy with it