I worked on a 5ver with the slide left out in a RV park that had water intrusion. The entire end cap wood and slide out floor and wall had to be rebuilt. Some damage was due to neglect and some due to the seals not making a good seal with the slide left out. Both of my BOL's have new 5vers, both are fighting water leaks on high end Montana's. Both rigs are 9 months old. A neighbor has a 2 year old rig with a rotten slide floor from leaving his slide out over the summer when not in use. My thought is why take a chance with when it is so easy to bring them in. Wouldn't think of leaving my four slides out on our MH when not in use.