Having in/out slates , snap n gaps are great,but so often I have seen poor compliance, and dependency on these things as a function of safety is not a good idea. Before there was a slate, I did encounter a diver entering Rocky Horror when I was exiting, and it was a difficult situation, as well as causing team separation and inability to respond to an emergency if either needed help. I have done Rocky Horror with the slate in place, and so often it would indicate someone in there, when we were the only team in the park, as well as passing an extended snap n gap at Martz. We basically quit trusting this and would put in another means to indicate we were there, and that was with a wet note page clothes pinned to the line with date and time.