I always pull one pack per time.
If I see a DPS pull more on their own, they will also be tanking that pack on their own.
If my healer get's aggro because of it, you're in a lot of trouble, cause I will save my healer, but I sure as hell will boot you from my party.

If you want me to pull more, you can ask, nicely.
And if the healer is okay with it then I will pull faster or larger groups.
But speedruns?
Not on my watch.