Quadratic voting approximates efficiency for a large collective making a sequence of binary decisions. What if a group can take multiple actions? Say, for example, a series of decisions where 2 out of 5 outcomes can be chosen each time.
I'd like to know if anything about the efficiency of quadratic voting is known in such situations. Does it depend on if non-winning choices can occur in later decisions? Also, what if different decisions use differing amounts of a finite resource that must be apportioned?