> Fast charge doesn’t seem to hurt.

For me a year is nothing though, my phone is on its 4th year, my daughter has my old iphone X.

Yes but if after 1 year I’m at 100% battery health then isn’t it reasonable to assume that what I’m doing isn’t significantly harming my battery and I can continue like this for several more years? On previous iPhones where I didn’t use the 80% charge limit battery health dropped mostly linearly over the 3-5 years that I had the phone.