Yes ~ nothing black and white in the DNA forcing only a 9 hour rule ... the 9 hour day is a 'recommendation' based on evidence in the field that children left in care longer than that start to have increased anxiety, stress and negative behavior ... 8 hours seems to be most children's perfect threshold, 9 hours is pushing it and over 9 hours and you can expect to have more end of the day accidents and incidents so I would be planning things that are quiet and calm to help reduce chances of behavior occurring in the first place!