'Bunching' doesn't help either. When there's no delay and 7 aircraft hit the stacks at the same time (not unheard of) the guy at the front gets no delay and the one at the back gets 10 mins. Now if the delay is already 10mins and the same scenario occurs the guy at the back will have 20mins.
Maybe we should go back to the days of giving either "no significant delay" or EATs as pilots clearly seem unhappy with our efforts at the moment.