As a healer, if I am bored and can handle bigger pulls. I inform the tank I can handle more. If he doesn't listen and continues to single pull, then I will just pull more mobs and stand next to the tank so his AoEs will grab the mobs.

If I am on my SMN, then I usually inform the tank that I am a SMN, literally the highest AoE damage in the game, and I'm not sure about other SMN, but I have an insane need to AoE massive packs of mobs and love to watch them die fast. However, if the healer/tank can't handle it, then I respect it. But I do tend to go by the "tank pulls everything" idea

When I go on my PLD, I look at the DPS to see what I'm working with, then do a single pull to see if the healer can handle it, then I start to do big pulls. If the DPS are taking too long to kill the pack of mobs, then I go back to small pulls.