In. Less chance of leaks and critters. Keeps your seals secure also. Just open occasionally wipe your seals off and clean. Keep oiled or lube to prevent drying out and cracking
Mine is about 50/50. Mine stays under a large pole barn and out of the elements too. During the off season they are in. From about March till Novemberish they stay out unless its gonna be a long spell between trips. Having 3 slides just makes it easier to get in and out as well as going in to check on things. I to recommend periodic attention to the seals with some sort of protectant.
Please explain. I'd like to hear why this is. Many live full time in their RV's with slides always out and I've never heard anything like this. My understanding is manufacture's actually engineer for the slides to be out most of the time rather than in. Not saying your wrong, just would like to hear why or examples.