If we are not actually using our camper, the slides are in. It won't hurt anything to leave them open all the time. Ours are open at home, pretty much year round as we use the camper at home everyday, except between January and February when it gets too cold to financially keep it heated. When we migrate back into the house, the slides are then pulled in.
The other time slides are in, is if we know snow is coming. Then I'll retract the slides (and we move into the house). Once the snow is over, they come back out and we're back in the camper.
Why? you ask?
Because, if the slides are out, and for any reason we have to move the camper and there is a foot of snow on the roof, the slides are not coming in. We just screwed ourselves big time.
Same with some serious Summer storms and tornado warnings. Button everything up, in the event of total power loss and we have to bug out!
If you are going to be gone from the camper (completely gone), I advise pulling the slides in. It will not hurt the camper for them to be out. After all, they are made to be out!
The problem is, what about all the unknows that could happen. What happens if for some reason, the camper has to be moved and you are not there? Slides out... it's not moving anywhere! What happens if the weather turns really bad and wind blows tree branch, a board, even a nail through the roof of one of the slide outs?
Face it, the smaller the roof, the less possibility there is for damage. A tree branch can fall 1 inch from the camper with the slide in. If the slide were out, the branch just crushed your slide. Why take chances? It's definitely safer for the camper against the elements, thieves, and trespassers for the slides to be retracted (in) IF you are not going to be there with it.
for what it's worth.