They have a strict model for traffic count/volume. They can run a full restaurant with one cook and two, maybe three waitresses. If a location is getting overwhelmed they build another one.

I had a friend who took a job with their construction/architectural department years ago, and he had to visit random Waffle Houses and record the number of customers vs the number who used the restrooms. I guess they were deciding if they'd go to two-hole restrooms or not.