Covers are known to whip around in winds, scuffing the paint, causing damage in multiple places. Difficult to install, difficult to remove. Prone to develop moss and other nastiness both external and internal as they age and the anti-fungals evaporate. Often seen as a sales scam by previous owners who abandoned them. This all depends on storage area and humidity of course.
Rule-of-thumb is to wander around your potential storage area and see what your neighbors do as the cold season approaches. Then do what they do, assuming you find many to compare.
Up in Fairbanks Alaska where I overwintered for 3 winters, I saw maybe 1 or 2% of RVs had full covers. Most were just parked with no cover.
What I did was watch the weather carefully as spring approached and then got up there and shoveled off the snow well before it broke the freezing mark during the day.
If you have a building you can snuggle the RV up against to block the winds, that would help.
