Totally agree! Next to Lies of P, Sekiro is my favourite soulslike and probably remains the one I've played through the most (possibly tied with Lies of P) and the one I'm probably best at. Even though I'm very comfortable with the base game of Lies of P and can knock out a regular playthrough pretty well, I'm just better at Sekiro. Once you know the parry timings of bosses, a lot of them become trivial.
I remember when I first tried the final boss (specifically not saying their name since I don't know where you've finished or if anyone's reading who's not finished yet) in my first playthrough... That was fucking rough. It probably took me like three straight days of attempts and a lot of guides to get it. Nowadays, I can usually first-try them without too much sweat. You just know what's coming and know what to do.