The attached image displays all the needed screens for every user story. The flow diagram allows all the stake holders to get an idea of what they are about to make BEFORE production starts. The idea is to get folks in a room and start banging on the imaginary product and come up with possible issues and suggested solutions.
Most lean process teams will have a very limited cycle of revisions and will often skip revisions of diagrams. In those cases we’d hot fix those changes, making revisions while an developer is building the UI.