How often do you guys start your car over winter storage?

Sounds like all of this is acceptable advice. My cars are stored inside, unheated and uninsulated. Temps don't get lower than 17 degrees, an then only for a short time. I start mine about once a month. But what is also important to me is to avoid flat spots in the tires. I jack up the car and spin the wheel about 45 degrees at least once during our 10 weeks of winter.