Depends. I'm not going to DPS on WHM or SCH if the tank is doing repeated pulls one after the other with big groups and not many breaks in between, I may be helping to kill everything faster, but I'm also draining the resources I could be using sooner. Usually I throw up Aero and Aero 2, and Swfitcast Holy on big groups and that's about it. If no damage is coming from the target, then I'll go ahead and Regen tank and DPS till a certain HP amount.