I'm not sure whether or not this is standard practice, but I've been taught that between two different-level headings, there shouldn't be any text. For example, the following would not be permitted (or is at least considered bad practice):
blah ← no text here
Following this convention, should all text be at the same structuring depth?
I.e. all text would be for example at X.Y.Z. level, and no text at A.B. level.
blah ← no text here (depth=1), because chapter 2 has text at depth=2
Note: I'm aware that chapters aren't supposed to stand alone (i.e. if there's chapter 1.1, there has to be at least a 1.2), but I omitted those for the sake of readability.