I typically try to ride at least 1 time a week on the off season to keep them ridden, but that cant always happen. If it has been a couple weeks / a month then yes I will start and run the bike on a warmer (above freezing) day maybe even roll it a little so its not sitting on the same section of tire. I have never been one to leave my battery tenders on ALL the time when I don't ride, but I will at least plug them in weekly for awhile. My reason for starting them is to just keep the fuel and fluids moving .etc. No science behind it just a personal preference of mine.