I never leave sails on the boat over the winter. It doesn't take much time at all to take them off. I always fold them so head ,tack, and clew are easily accessible. They are bagged and hung in a garage closet where no critters can get at them. Anyway, winter is a good time to take them to a sail loft if they need repair or cleaning. Putting everything back together in the spring only takes me about an hour. The jib slides easily up the groove in the roller furler. With the sheets attached beforehand, and the foot pulled back, it's a simple matter just to roll it up. With the main, I just put the battens back in their pockets, attach the clew, and the tack, clip the halyard to the headboard and feed the slugs Into the mast track one at a time, alternating folds as I go. I have a lazy bag so the sail doesn't have a chance to get away in the process.
One person I know left his sail on the boat during the winter, and a stray cat chose that as a place to have a litter. The smell was such that you could tell if his boat was upwind and relatively close for a long time after that.