Special Delivery

Tonight, I just learned something new. We 'subscribe' to a diaper delivery service. As in, at specific intervals, a batch of diapers shows up at the front door. Brilliant... Cept... How do they know how many diapers to deliver when? Did we fill out some form? Is there a baseline formula to predict how many poops a specific baby will take during a specific interval of time? Or did we keep count and record each one, and order based off that? Are there different levels of service, a la netflix? If my baby suddenly becomes more regular, can we up the frequency? Alternatively, if he gets stopped up, can we reduce the number of diapers that get delivered, so we dont have a massive back-up? (of diapers.. i mean) By default, if we are in this specific situation, there already is a massive back-up.. Ah, nevermind.