Per the book “Breaking the Vicious Cycle” the only stage is the intro stage which is 5 day maximum. A few items have rough time tables for introduction like nuts and coconut milk. Elaine believed that the diet would be additionally restrictive with stages.
PecanBread was developed for kids with autism and has stages/phases. If you choose to follow those stages/phases that is up to you but they are not required. >>Pecanbread Stages Link<<
Under no circumstances do you stay on any stage or keep eating the same foods because you are not symptom free. You are to expand your diet for maximum nutritional intake and to keep yourself from become intolerant of the foods you eat all the time. Do not keep eating the same foods day after day. If you have a setback with a new food that you introduced just stop eating that food for a couple weeks and try to introduce later. But keep adding other foods