Shit UX
How do you know when to reapply? Notice when a tiny icon in a sea of icons start flashing and disappear. No timer showing time remaining, no obvious visual (SB is the most obvious, and even then it can be easy to miss other people not zooming around).
On my Grav/Emp, I try to keep Fortitude up on ~4 people constantly, Mystic Fortune up on everybody, and if there's enemies that like using mez, CM up on anyone that needs it (not quite high enough for AB), but CM is probably the hardest to maintain up time, because Fortitude I just cast every time it recharges (can notice that at a glance how long until it'll be recharged), MF has a long duration, but CM is in that sweet-spot-of-suck, with a short duration, quick recharge, and no good way to keep track (short of installing HeroStats and using that).