I lived in my fifth wheel for four years. It had five slides and one of them was a long slide with the couch and dining table. Slides stayed extended year round and I never had a problem with anything except the slide topper on the long slide would sag over time. I never worried about it and I never really had problems.
I now have a smaller RV with one big slide which we just use for camping. I keep it plugged in 24/7 with the AC set on 78-80 and I keep the slide in for no other reason than its less volume to keep cool while not in use.