When to use Cure 3 or not

[Spoekes]

[list][*]When tank pulls >5 adds, WHM steals 1/2 of them. Self-cast Cure III in proximity to the tank and wait for Flash Spam to take back the adds.

I'd rather swiftcast me another Stoneskin first instead of driving my healaggro, that is above the tanks at this situation anyway, to the very sky.