Information density

The conventional idea in nonfiction writing, I think, is that a word should have one referent, a sentence should have one idea and a paragraph should have one topic. A collection of paragraphs, i.e. an essay, article or chapter, should have one theme, and a collection of chapters, i.e. a book, should have one subject. The problem with this conventional notion is the varying density of the ideas. A paragraph-sized idea to one writer is a book-length idea to a different one. Because there is no accepted standard of information density, it varies greatly from author to author. This comes at a steep cost to readers who have to determine what information is valuable and what is not.