I remember when I played an older JRPG with a very deep combat build system, as well as some insanely difficult post-game content that forced you to use said system.
Ultimately, I created a build something like where every party member had 4 slots of effects I could use on them. For each party member, I set it up as such:
Chance to heal when taking damage
Chance to heal when taking damage
Chance to heal when taking damage
Chance to heal when taking damage
And there was another effect you could put on the dungeon, where every battle would be subject to this effect. For that effect, I put in "healing spells are increased by 200%"
So pretty much everytime any character in my party took damage, they were healed back to full.
But even with this practically invicible setup, bosses would STILL kill you because your chance might not go off, or they would hit all your party members so hard at the same time you all died instantly because you were foolish about your positioning.
But the point is that the game pushed you to find exploits because the bosses at post-game were so insane you needed every advantage you could muster.
I miss that feeling.