Mine sits in the side yard because I don't have any option for indoor storage. I start it up and drive it up and down my road once in a while to keep the battery up, keep the seals wet and ensure the gas doesn't go bad.
People with $40k+ machines probably have a different routine than me
Same. Not with SxS specifically, but a few different types of gear and vehicles.
OP, the battery needs recharging, and the bigger the battery and the bigger the engine drawing off it during startup, the longer it needs to run to recharge the battery. Especially before it gets subjected to sub-freezing weather again. For a full-sized vehicle, that should be about 15 minutes at highway speeds, unless we're talking sub-zero weather, in which case it will need more. I've killed a few batteries in a year or two with daily-driver trucks in sub-freezing temps when just going from one side of town to the other in 15mins or so, not getting up to highway speeds and not being trickle-charged after. If it's a vehicle you rely on, especially in an emergency, keep it trickle-charging over the winter.
@WeiserBucks ' points about gaskets and seals is important too. Without being wetted through activity, they'll thin out, dry out, crack, and leak. Modern oils, especially ones engineered for high-mileage vehicles, often have additives meant to swell the gaskets because of this. But that doesn't make up for them just being left mechanically inactive for months at a time.
The only other thing I could add, would be to put some fuel stabilizer in the tank if it'll be sitting more than maybe 6 months or so, as older fuel can turn into a kind of shellack inside the fuel lines.
