Watching this video back, I noticed that when the enemy has multiple text boxes but only one health bar, skills that target all text boxes seem to be a waste: Despite multiple numbers showing up on the screen, it seems like only one of those numbers actually goes through as damage.

Considering the all-targets skills usually cost more SP, it seems like you'd be way better off using single-target skills in those situations. Like, maybe four times as effective (e.g., instead of doing 500 damage for 200 SP, you could do 1000 damage for 100 SP, or 2000 for 200 SP total).