Listen. I hate procedure. I will make things up constantly, fudge numbers, and operate purely on vibes whenever I can.
That said, Errant is a staggering accomplishment in applying procedure to every aspect of a fantasy adventure, allowing you to flesh out your players actions and make them earn their victories in a cool and engaging way. (I especially liked Lockpicking and the Magic/Grimoire system.)
All told, you can't make me follow procedure, but Errant will have a permanent spot in inspiring how I design encounters for my players.