Personally I don't think it can be a bad thing just to keep everything moving. I used to do the same when I had motorcycles. During the winter when they didn't get ridden I'd just fire them up a few times and let them run for a bit. The only difference is I cycled them through the gears as I always used to keep my bikes up on a paddock stand. Quite scary looking back cos I had one bike up to some stupid speeds up on the stand in the garage! If it ever came off it would've been carnage. Sounded bloody good with a race pipe on doing 150 in the garage though