Rubber mats serve purpose as far as: easier for you to clean stalls, prevent horses from digging holes, keeping stalls cleaner and drier for the horses. I have only seen dirt surfaces, havn't come across any concret or wood as of yet. With the dirt the saving tend to get very dirty fast and create mud, which is much harder to clean up. Also, if you have a digger, boy do you get large holes and fast! By investing in mats, it cuts the cost in the ammount of saving you use and also labor involved.