I think the stop sign is effective - but I also think it is overdone sometimes. To me the stop sign is one step from a technical. If I put up a stop sign and the coach runs it, I have no choice but to write the ticket.
Many times I'll see the stop sign go up when a coach is just doing a little chipping.
The higher you go, the more they will chip. At the subvarsity level, I don't tolerate much. At the varsity level, I take a bit more. It goes with the territory. Your hearing just has to get a bit more selective. Only hear the time-out requests
It doesn't hurt to talk to coaches, either. I always try to talk them down off the ledge before they throw themselves off it.
Rich