Here is a quote from the notes in the Book documentation:
Why only two levels?
Two levels are generally enough for all books, three levels may lead to poorly structured documents. The Book module is designed for the creation of short multi-page study materials. Consider uploading a file in PDF format for longer documents.
https://docs.moodle.org/34/en/Book_FAQ#Why_only_two_levels.3F
This is a philosophical statement about the book: "Two levels is enough, and if it is not enough, the problem is bad design"
So it is with sections. The section is the basic unit of Moodle. Inside this we put activities and resources. Considering an average course, too many sections and we get the Moodle Menu scroll of death. Too few sections and we get the Moodle section scroll of death; unless you have a very small course with not a lot of entities. In my opinion, one way to deal with this is to code to allow sections and subsections. Average course: 10 sections, 4 subsections per section, 5 bits per subsection. From this scenario, course design considerations could solve every problem.
The documentation for such a suggestion would read like this:
Moodle 5.4 2022: release notes.
Die Scroll of death Die.
Announcing our latest attempt to improve the Moodle scroll of death. From the next version on we have a new course format. The simplest view of this has sections in the new Boost menu version 5.0. The menu is totally customisable, but is built around the sections in your course.
Each section functions as sections did in the past; by default you get one piece of screen real estate to add content and activities.
However you can add a subsection. If you add a subsection, in the basic view you immediately have to tabs at the top of the screen to access two pieces of real estate. You then have a default name for tab 1 ('Overview') but you have the ability to name each subsection; short names are better since they are tabs . .
ie Boost menu to access sections; tabs across the top to access subsections.
This architecture is very flexible in it's coding, and other course formats are possible to build the course>section>subsection UI in creative and smooth ways. There can be various ways developed to navigate section to section and subsection to subsection; for now it is two levels side and top (on large screens) and a cool new mobile responsive UI.
We are making some assumptions here: that the number of subsections per section is small, so that the tabs solution works; that to keep this number down is a matter for quality course design. And no-one should need sub-sub-sections.
In a further magnificent feat of coding, we have a course overview page where all the subsections are listed, and may be re-ordered by drag and drop, renamed with inline editing, and various other parameters set.
Terminology: We may change the terms to TOPICS (sections) and SECTIONS (subsections). So your design consists of creating a course flow using two levels of content, and usually a students will engage in one TOPIC and then switch back and forward through the SECTIONS in their learning. No more Scroll of death.
I've made the rather whimsical piece above as simple as I can, but I don't have time to really make it clear.
As of today, I do not know of an elegant solution to the scroll of death. IMO. The 'nearly elegant' solutions require either complex coding or plugins, new course themes or course formats.
My 2c. No more time to try to think clearer, but feedback and comment is invited.
-Derek