I visited a local restaurant recently that had all you can eat tacos. After serving the first plate of 4 small tacos the waitress came back and told us they were out of taco meat so they were no longer serving tacos. We paid our bill and left vowing never to return.
This restaurant also had all you can eat fish that they weigh down with grease or oil so it is really heavy and weighs down in your stomach. After 6 pieces you feel like you've eaten 18 pieces of regular fried fish.

I'm surprised more 'all you can eat' restaurant do not incorporate this strategy.