Yep, move it once in a while... Better than staying stationary long-term. Cars that have "closed" wheels where you really cannot see the rotors don't have this problem - Ive verified this by parking my BMW and my truck in the same spot as my saab, long-term (weeks). The saab has quite rusted rotors after the first rain, making loud first stops... Nothing after weeks of sitting for the BMW and truck... both of which have far more "closed" wheels.
I'd say wheels are 80%, use is 20%... cars can sit for a LONG time if the wheels do not expose the rotors.