The issue of keeping the mat sides clear is definitely alleviated by policing. It is also important to note that just good old fashion common courtesy goes a long way in helping with this as well. I know when my wrestler is on a mat at the opposite end of the gym, I always leave the stands. If the stands are full at the other end or if I would have to displace a lot of people to get a place to sit, I will stand mat side. I am always careful to position myself so as not to block anyone else’s view. I appreciate when people show me that same courtesy, so I pass it on. For the most part, I don’t feel people are trying to be uncaring; sometimes you just get caught up in the excitement!