Storytellers or Authors?

"Only mediocrity can be trusted to be always at its best. Genius must always have lapses proportionate to its triumphs." -Max Beerbohm

Is it fair to say that most authors who crank out a book every year (or more) are mediocrities and our best authors only deliver a book once every few years? Or are those annual authors actually "storytellers" who fill our mind with wonder over a short period, while "authors" feed our soul forever?