It doesn’t work though. He can’t just start is clock for 5 seconds every time the ball goes out of play. Let’s say a normal GK takes 25 seconds from when the ball goes out to when it’s restarted. The ref can’t decide at which point they have “taken the piss” everytime. Especially when ball boys and the crowd are complicit with the time wasting.
Ref shouldn't even be in charge of it. Independent timekeeper who works based on rules to prevent time wasting. Stopped whenever a player goes down, if someone takes more than 30 seconds on a goal kick, when a goal goes in etc.