These days it rarely is, at least for me. It's virtually always reserved - to be paired with a tank immunity.
All that being said.... when I do get to save it for an emergency I actually kind of like it? There's been enough times where a DPS eats something that brings them to critical hp, but they won't be dead until a raidwide hit or something goes out in the next second or two. It's enough time for benediction to save them, if I have it to spare. The majority of the time benediction is reserved or on CD and so they die. But when I can spare it, well... it is nice to have a tool for those situations.