Bosses in this game seem to require counters. If you don’t counter, or don’t attack in the scene immediately following it (you can attack in QTE cutscenes), the boss will cycle back and start its pattern anew until you do the QTE again. Often “defeating” a boss means they’ll show their counter opportunity.
Successfully completing counters can decimate the amount of time spent with a boss. You can dance around certain ones for fifteen minutes, only to crush them in mere seconds if you manage to RNG two counter opportunities following each other.