What I'm starting to realize is that this battle system just doesn't flow well when fighting a singular big enemy. The ideal flow is to build up your combo gauge -> consume a 1/5 of the combo gauge to fit in a big hit and reset the combo -> repeat. You build up the combo gauge by inflicting status effects, killing enemies or doing a perfect dodge (kind of). When fighting a group of random encounter enemies you can easily get into that ideal flow.
Boss battles are a different story. You can't refuel by killing enemies if there's just the one obviously. A lot of bosses seem to just be highly resistant or immune to status effects so you'll try to hit them dozens of times and nothing happens. So then is the solution to do perfect dodges? Maybe but there's a weird thing about those. It seems like you only get one gauge bit from doing a perfect dodge when you're under 3? Maybe? Or it might be on a cooldown? I'm genuinely not sure how it works. But the point is you can't just spam perfect dodges to fill up. And that assuming you can perfect dodge them. A lot of enemies, including bosses, in this game are not animated with the wind-ups an tells you need to have to make a dodge mechanic reliable and satisfying.
It's weird because it seems like they realized this at some point. Every once in a while, especially in the first half of the game, boss battles are against groups of one commander and a bunch of minions. Sometimes bosses will spawn enemies during the fight. But then you have a significant amount of boss fights against 1 guy who will just not let you do anything the system is designed for and you end up slowly, tediously grinding them down with chip damage.