What care tonneau covers need in winter?

What care has to be applied to tonneau covers during winter?
I can observe some owners of hard tonneaus, taking them off their trucks, and storing in garages till the spring time.

Others, particularly those with soft tonneau covers apply certain creams and waxes, trying to minimize the impact of low temperatures, that make the plastic brittle. Still, what use of the poly cover if you can't stretch it because of the worries that it'll break up?

The best situated are those truck owners who have metal canopies, that are properly sealed to the cargo box. However, there are only few of them, because of the initial cost involved in purchasing the tonneau cover.
It would be interesting to know, how other drivers are dealing with the adverse winter's weather on this important truck accessory.