If I remember from our trip last summer, the ADRs were for non-peak times (before 11:00, after 2:00). We did a walk up at 12:30 and the place was only half full and didn't fill up the hour we were in there, which I found very surprising. The year before when it was ADR only, it was full. Makes me wonder if their walk-up strategy is a good one for them or maybe that day was an exception.