I purposefully haven't said periodicity or something else (maybe I should have added a bit more detail anyway.) The ebb and flow, the up and down the cycling is known, but when and its magnitude is not.

Sure it's chaotic and it probably has scale-free (self-similar or fractional-dimensional) properties at certain regimes, but on the large scale it's pretty well approximated by dynamic systems. (See the micro founded macro models used by central banks.)

Of course, we're getting better at modeling both micro and macro behavior of economies. (The caveat is that the economy also evolves so old models usually get less and less accurate, so job security for econometricians.)