Commonly you will have a relatively broad goal of providing some functionality by the time a project is done. Every sprint, commonly two weeks, you concentrate on producing a piece of functionality that will get you closer to that goal. At the end of a sprint, many teams are expected to have what's called a minimally viable product that is technically usable. The problem with that concept is MVP almost always becomes production. That results in poor coding that is hard to support. It almost always involves rework later on, often when something is already in production. And you are not crazy. Not having a clear idea of what you're coding for is wasteful and very inefficient.