No. The size of the sponge is not related to how much filtration goes on. The flow rate of the water is what you need to concern yourself with.
Water flowing at 10gph through a sponge 2"x2" will give the same filtration as 10gph through a sponge 5"x5".
The only difference is that the small sponge would need cleaned more often.
Hope this helps.
A properly operating air driven sponge filter is mainly a biological filter. I find that one to two cubic inches of sponge per gallon works good, this of course depends on your bio load. I run home made sponges that are 4" cubes, one in an overstocked 29 gallon takes care of the bio filtration fine.