Will adding more yeast to a dough mean I need a longer time in the proofer?
Yeast is a living organism, and the rise in the dough is a result of its metabolism.  As it lives and grows, it emits carbon dioxide as a waste product, which metaphorically blows up the dough.

This means that more yeast you have, the faster it raises the dough.

The rate at which it does so is a function of the absolute amount of yeast, but the amount of yeast grows exponentially over time, where the rate of growth is related to the temperature of the dough.

This means that for dough held at a constant temperature, the amount of time it will take to proof would actually be less if you double the initial quantity of yeast, as each generation of yeast would have more cells in it given the larger starting quantity.  



The proofing temperature is extremely important; what make take a given amount of yeast an hour on a hot summer day might take 24 hours at refrigerator temperatures.

The flavor of the dough is also related to how fast it proofs; longer proofing times generally develop a deeper, yeastier flavor.  So bakers tend to control the flavor development by adjusting both the initial quantity of yeast as well as the proofing temperature.