The reason why pausing works is because it resets the wait/attempt timer. If the client asks for a WU and there isn't any it will wait some random amount of time (lets say 35 min) but if you pause and start it again it will do an attempt immediately and fail but the timer will be set to something like 1min 36 seconds and it will try again. If you watch it and keep pausing and restarting it you'll get more attempts but you'll only get a WU if ones available.