For Me ; The creation of individual pieces of the map generates questions. Why is this here? What is the purpose of that? How do the people/creatures live? The answers to these question give direction to the maps development. On the other hand as the map develops it also fuels more questions. This continues one part the map feeding the story and the story feeding the map. The story begins to Demand certain features of the map and the map starts to adapt a certain feel or flavor based on the developing story. In the end they become intertwined and parts of a whole. A word of warning ! From my own personal experience the danger to this type of development is sometimes the story demands more than I have the skill to deliver. Then I have to settle for the best I can do Now or rein back the story to fit What I can do well now. This leads to a folder of I'll redo this later !