Henrik: I think you only get stuck counting levels if you fail to write in topics. If you create a topic (think of a magazine article) then you'll probably only ever need to divide that material into one or two levels.
I think of H1 as being a topic title wherever it goes. It never gets adjusted. It's always H1. An H1 can be divided into H2s and, if necessary, the H2s into H3s. A single topic can be made into a small document -- like an installation sheet. In that case, HT (document title) and H1 (topic title) are the same. Several topics (but too few to require grouping into chapters) can be assembled into a medium-sized document, like a user guide or a quick start guide. So you'd have HT and a series of H1s, with the H1s still divided at most into H2s and H3s. When there are so many topics they must be grouped, I group them into chapters. So a chaptered document might have four levels: HC, H1, H2, and H3. Beyond that, I flatten the material into the desired number of levels. I only get trapped by my own levels when I'm stuck thinking about an outline or about the logical nature of the content, which is not what my end reader needs. Bear