What does "stoichiometric amounts" mean?
Sometimes, practical chemistry does not work like it's supposed to on paper. A perfectly balanced reaction equation may dictate that two reactants should be in a 1:1 stoichiometric ratio, but in practice, you get much better yields or reaction times if you use an excess of one.

When that happens, you are no longer using a stoichiometric amount, as specified by the balanced equation, but a super- or substoichiometric amount.

Welcome to chemistry in the real world.