To add in at the end here, I think if I were to be storing a model that looked more like an appointment request and not the appointment itself it will be pretty easy to just ask for the last stored appointment request, check its data and figure out what step in the process I am on and therefor where to return the user in the view. A singleton repo (in memory or not) does sound like the best place for this. If its behind an interface it doesn't matter where its stored.