I would add that...
As a healer if you end up spamming your healing spell THEN you have to realise that something is highly wrong
Either you have a gear problem (never happends) or the tank is squishy or not popping cd (very high probability)
Or he stand in aoe

Most of the time a pull big or not in dungeon is :
Wait for stone skin to break
Wait for the tank to reach 70% Hp
Cure II and regen
Finish the pack
-> redo the heal if regen end or if the tank is near 50%

On massive pull same start but you pop
Divine seal + medica II + regen + asylum
And then free DPS time (with some holy when the tank is mid to low life to let the 4000 regeneration tick)