It is a bit grindy. Particularly for mages, which is one big frustration I have with the game.
Take the current Fire Powered Ship event, for example. I know that (a) the boss at the end has many, many times more HP than any other enemy in the dungeon and that (b) it's weak to ice, so it's definitely worth taking a black mage with me. In my case, I've been using Terra, equipped with a 6-cast Blizzara and a 4-cast Watera (since I know one of the enemies is weak to water and dies in one hit). That gives her ten useful actions for the whole dungeon, but I'm saving six of them for the last round of the last fight (I've needed every single one of them every time), so she effectively has four actions for the first fourteen rounds. In at least ten rounds she's going to left with nothing to do. I could make her attack, but that might risk my Champion ranking at the end, since she's not going to kill anything on her own. I sometimes make her defend but she's pretty tough, so I usually just leave her alone completely.
If I want to do something about it, say by levelling up my Blizzara to 8-cast, I'd need 30 Lesser Black Orbs and 45 Lesser Ice Orbs. I currently have 28 and 17. Getting another 28 Lesser Ice Orbs would take me ages - I can only trade in for ten through the event - especially since I only need one more (normal) Ice Orb to be able to create Blizzaga. Of course, there's no incentive for me to create Blizzaga because it would only be a 2-cast ability, and that would make Terra even more useless, for the time being.
My three fighters, on the other hand, can attack every turn, can take down every regular enemy in the dungeon with no more than two hits, and can save all of their special abilities (like Double Cut, which is great) for the final boss. That's why my best fighters (Cloud and Sephiroth) get so overpowered; any time I'm in a long or difficult dungeon I put them straight into my party.
TL;DR: Honing abilities should be cheaper to make the game less of a chore and more fun.