If I'm not riding, I'll run my bike once a week or so just to get the fuel through the carbs. If your bike is FI I can't imagine it needing to run but maybe once a month, especially if you put a fuel stabilizer in it. I'm pretty sure gas doesn't start to crum up until it's been a few months so for the most part most winters are probably short enough so that it won't happen. With that said, I try to ride whenever I can so I at least can refill my tank with fresh gas.