slide in or out over winter ??

I keep my slide in. Don't want ice/snow on top of the slide, melting down the sides. Plus, IF something goes Ka-Flooey , I can take if for service. If the slide is out, I'm stuck trying to get the slide in.

Leave it in or out, never partial. The side gaskets only seal when it is either fully retracted or fully extended. Nothing wrong with leaving it out, I will do that if I am working in the TT in the off season. Bear in mind the roof on the slide is usually thinner than the main roof and susceptible to snow load. If you leave it extended pay attention to the weather and if you get deep accumulated snow clean it off as soon as you can. Also if the slide is out and you have ice formation, do not attempt to retract the slide...the ice can tear the seals.

Other than that there is no reason you cannot leave it extended. That said, if you are just storing the camper and don't plan on either living in it or working on it, best practice is to leave the slide retracted.

The reason I leave mine out is that it gives much more shade to the tires on that side. Even with covers on, that is the sunny side and in AZ, anything you can do to protect the tires from sun damage will help in the long run.

Our manual suggests that it is in for storage. It really makes sense to keep it in. With ours in the whole trailer is still 100% of use.

I know lots of people leave them in. I've had a slide since 2004. I've always left mine out and I've never encountered a problem with leaks, wear or tear. I do lubricate the slide gasket every three months though.

I'd keep it in, until you're ready to go out there to work or whatever.

WodGlue

As I drive around the state I see many TT's and fivers that I know have sat in one spot for a long time. Almost invariably the slides are in the out position. It seems to me the slide is most vulnerable to leaks when it is extended, so it would make sense to store it closed, I would think.

Unless it blocks interior access I'd leave it in. In fact if it did block access I'd just move it out as needed, but mine's not under a roof and will have the battery removed during storage.