Until you are half way into the game you don't get access to a decent group healing spell.
80% of the enemy acts in the game are enemies spamming attacks that hit your whole party for 1/3rd to 1/2 of your HP. Almost every boss cast act twice at the start of the battle and usually just spams party hitting spells over and over again.
Because of the overdrive bar you can't even always heal when you want because both your actions and the enemy actions drive the bar higher unless you take an action you don't necessarily want to take to mitigate the bar.
Late game bosses cast act thrice and or summon minions with those same group spamming spells.
Sometimes fights came down to redoing them until it worked out that the boss didn't down my healer or mage. Many times had to put poison and bleed on the boss and spend the rest of the fight managing the overdrive meter, keeping everyone alive, and keeping those statuses on the boss until it killed them.
66 hours into the game. Did every side quest presented to me. Did about 2/3rds of the reward board.