Discounting space rent when mobile homes are empty

One more questions smart gents…Just purchased a small mobile home park. The manager who ran the mobile home before I purchased it gave discounts of the space rent to the owner of the mobile homes on the property when the tenant moved out of the mobile home. For instance normally he would charge 80.00 bucks per space…but when the tenant would move out, thus leaving the owner of the home with no rent…he would then only charge 40.00 for the use of the space until the mobile home was occupied again…then he would charge the 80.00 for the space rent once someone moved back in. To me that doesn’t seem smart. I figure rent should stay the same, rented or unoccupied. Do any of you ever make concessions like that? Or have you heard of others doing the same thing? I think that is asking for trouble especially if I manage the place from some distance. Would some of you mind sharing your brief thoughts on the matter?