Speaking from a Bard's PoV, they have several passive buffs which will almost always be on, and several that have a 15 second duration (30 or more seconds with talents). Basically it seems you'll be dealing damage (and healing) with Cadence, and refreshing the buffs every 30ish seconds so they never fall off. It's not a precise timing, but you don't want your buffs to fall off, for sure.
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