Cold Climate Folks: how often to run your C in the winter?

Once she is sealed up for the winter she stays that way until spring. Winterize, take out the batteries and put them inside heated garage. Would be harder to start and probably more damaging to try and get it to turn over or MAYBE start at -35/-40. Can't drive it when it is buried up to the tops of the wheels in snow. Come spring reinstall batteries, clear water lines and go. Never had a problem.