In a discussion on why subsubsections are evil, egreg comments:
If you have subsubsections, you must have at least two of them in a subsection; you must have at least two subsections and, of course, at least two sections. Draw the tree and you'll understand.
When I'm writing long texts, such as for my thesis, I might have sections that contain only one subsection. For example:
5.3 Topic X ... bla intro bla ... 5.3.1 Special Case in Topic X ... bla detail bla ...
Is it considered bad style to have
5.3.1, but no
5.3.2? Should I rather put the
bla intro bla in a
5.3.1 Introduction and have the special case in
5.3.2? What are the general approaches here, what is considered good or bad style, and why?