I'm far from great, played pretty casually and I beat in over the course of a month in just under 60 hours, but I'm a completionist and spent my time beating every available mini boss, hunting down items, etc. Most major bosses took me between 1-3 hours to beat, and it really just comes down to timing and muscle memory.

A lot of people complain about the lack of gearing up and leveling to overpower roadblocks, but at the same time it's much more rewarding to feel yourself improve rather than grinding out stats or leveling magic to cheese a boss. At the same time, there are lots of things you can do to give yourself more breathing room like new skills, gourd seeds and prayer beads that extend you life and healing.

People also complain about there being only one way to beat most bosses, but that's not true at all. The prosthetic gives you a wide variety of tactics, and you don't always have to face tank enemies with deflects, as you can focus on dodging and running on most bosses if you really want to. That said, the easiest way to win is to just become a deflect god and time you blocks well.