It is also notable that the Feynman lectures (3 volumes) write about all of physics in 1800 pages, using only 2 levels of hierarchical headings: chapters and A-level heads in the text.
It also uses the methodology of sentences which then cumulate sequentially into paragraphs, rather than the grunts of bullet points. Undergraduate Caltech physics is very complicated material, but it didn't require an elaborate hierarchy to organize.
A useful decision rule in thinking and showing is "What would Feynman do?"
