Looking at a picture like this reveals so much that is missing when only looking at Emacs or Vim. Classes that violate the Single Responsibility Principle may become obvious because they’re related to too many other classes. Cyclical dependencies might be identified. Even class names may be brought into question. These discoveries are not very obvious when writing code, but they were remarkably obvious once we threw the structure up on the whiteboard.
I almost always have some kind of notebook and pen by my side so that I can doodle words and shapes. Having a whiteboard nearby is even better.