I think it might depend on how big the seed potato is to begin with. Last year I bought a little net bag of seed potatoes and none of them were bigger than a golf ball. I planted the whole potato and this is some of the harvest I got.
Maybe next year I'll try an experiment: cut the golf ball sized seed potato in half making sure each piece has an eye and see what happens. Maybe I will get twice as many large potatoes, I don't know.