I play a lot of buff/debuffet characters and I will reapply buffs whenever possible, if it's an AoE I will pop it off when the most people are gathered, generally when we enter missions of in the middle of combat. The one habit I did have to break myself of is trying to heal everyone regardless of where they were. Sorry, but if you run off on your glass-hammer and get in over your head I will not go harrying off away from the main group (or tank) to save your bacon at the risk of my own character's health.
I don't assume that anyone is soft-capped because then I don't have to consciously think about when or who to buff. Kind of like using a turn signal, if you always use it then you don't have to think about it, you just do it.