# How to choose which reactants to have in excess?

In a precipitation reaction, how do I know which soluble reactant I should put in excess? E.G. $$\ce{Na2SO4 +Pb(NO3)2 -> PbSO4 + 2NaNO3}$$ In my book, $\ce{Na2SO4}$ is added in excess, but can we add $\ce{Pb(NO3)2}$ in excess?