It depends on which of the three Cabbage worms you are discussing because one does overwinter in most of the USA as a pupa while the others migrate as adults. Harlequin bugsm and other stink bugs, overwinter as adults in "weedy" patches which is why that advice to clean up your garden in the fall which will also clear out any place for the predators, such as the assasin bugs, to winter.
Floating row covers can be one means of insect pest control, but you should not rely on them as the sole means of control.