I don't main WHM, but I'm currently levelling it up. Every pull I usually wait and see what I'm to expect (if a tanks HP is dropping rapidly, I'll most likely have to heal and not DPS. If their HP drops slowly, then I will feel comfortable DPSing) and if I can DPS, I throw a Divine Seal'd Regen and Asylum over the tank and begin the Holy/Stone III spam.

I try to do as much as possible, otherwise I'd be bored :I