You also have an agile option: release early and often! Use the feedback you get from users/customers to decide what to do next and when to stop. The problem w

You also have an agile option: release early and often! Use the feedback you get from users/customers to decide what to do next and when to stop. The problem with waterfall approaches to "fixed" endpoints is that at the beginning of a project you know the least. It can be comforting to imagine that you can fix an endpoint up front. But most projects worth doing result in a lot of learning along the way. I have heard of very few projects that did their 1.0 release and were so successful that they just stuck with that release forever.