Does anyone run an extended lunch time with teachers assigned to be available to work with kids during part of it?

I know I talked with someone at last year's AP Conference who runs a schedule like this- 50 minute lunch, teachers are assigned to eat 25 minutes/ work with students the other 25. Kids have the whole lunch hour to eat/ work with teachers in whatever order works based on which teachers they need to see. I'm wondering about details- supervision- problems you encountered and solutions for them- etc.