The _working/ directory is a scratch space purely for your use.
As you are working through a problem, always write notes to the _working/ directory. These notes should include both your observations, and your deeper thinking on how they relate to the problem at hand or the overall project. Make sure they have a clear structure and are easy to follow.
Use the _working/ directory as a place to brainstorm and plan your upcoming work. Try to structure your notes in a way that is easy to follow, understand, and pick up later.
You may delete files in the scratch space when you are done with them.