Tarana, Game of Thrones isn't an ideal example for me. I had trouble finishing the first book and haven't gone back for any more.
Still thinking about this, and there is another way to play with the sub-chapter idea, but it reverses what I said about not needing to take additional care to introduce the character at a change of context. But, hey, am I a writer or not?
If I rewrite the opening paragraph of each new section (sub-chapter) to start with the character name then I can use drop-cap/initial formatting as a way of making it stand out a bit like a sub-chapter heading. I'd still use the "- - -" breaks in case some ereader formatting stuffs up the initial.
Chapter 10.
Carla said ...
- - -
Ruth wondered ...
- - -
Matt thought ...
- - -
Of course, having reworded the opening paragraph the highlighting is largely redundant (and could be a bad thing, since I sometimes find that overly fancy initials just make the text harder to read). Just a thought. As if I really needed yet another choice. I might put off finishing the story just to avoid having to decide.