When leveling up low level characters and doing Hunting Log entries above my level, like when I did Rogue for example, I would cross class Protect, cast it, and then swap out to a different skill since it usually lasted me as long as I needed (up to 30 min anyway) as long as I didn't change classes or level synch for a fate. Swapping out cross class skills will usually trigger a 1 min cooldown so that's something useful ahead of time when first going to a class to solo stuff, vs. on demand.

It's not necessary of course, and besides not available as cross class actions to a lot of Jobs once you move to those, but it's helpful early on when not level synching for fates or going in and out of dungeons.