While obviously I'm going to change my loadout for different bosses, I find myself relying less on abilities for bosses except for the occasional elemental weakness and retaliate + double cut meta combo. I find certain mobs are far more dangerous, for example if something manages to blind one of my fighters early on (and I don't feel like wasting a slot on Blindna) or if five monsters gang up on one character. Also one action to kill five mobs helps achieve that 'actions taken' condition for mastery.

I also try to keep in mind that mobs can randomly drop refills for abilities, and if I don't have everything earmarked for the boss I can actually sometimes get 2 - 3 uses per encounter out of a normally 1 use summon that hits everything on the screen for harder than my Soul Breaks.

My party's far from ideal though. I'm using Rinoa as a white mage for some reason, until I get Lenna up in level I guess. Her job is mostly to Boost Cloud while Josef and Cyan do the Double Cut + Retaliate combo. Rydia just pokes things with a stick unless she can either blow up the boss or summon when to convenient.