In my editing work, far too often I come across papers that have headings numbered like {1, 2, 3, 4, 4, 6} or {1, 2, 3, 5, 6}, etc. Likewise, tables and figures are misnumbered and references are not in alphabetical order. Now I claim that no one is writing their papers on typewriters anymore, nor are they writing them out longhand. Nearly 100% of authors today are using computers.
Now think about that word “computer” for a moment. What does it mean? In its simplified meaning, “to compute” means to count. So why do people manually assign numbers to the headings in their documents, only to get it wrong in the end. The computer’s purpose is to count and enumerate these things for you. And the computer won’t get it wrong, even when you move entire sections or chapters around in your document.
The basic problem is that if you are using a word processor to write letters, memos, papers, reports, or even books—namely structured documents—you are using the wrong tool for the job. The proper tool to use is a text processor. Personally, I recommend LaTeX, but there are many other choices out there.
The main point is that writing using a text processor, as opposed to a word processor, allows you to separate content from style. You, as an author, should focus on deciding how to structure your document (the major and minor headings) and what text to put in your document, and not on deciding how the document should look. You should decide the latter after the document is written, and let the computer handle the work of enumerating and managing headings. The longer and more complex a document is, the more important this becomes. Word processors do an absolutely horrid job of maintaining consistency across a document. Text processors, on the other hand, do this trivially.
Free yourself from the madness of the word processor today! Just follow the two links above to get started, and have your computer work for you, not against you.