The traditional three act structure means books and movies often start with plenty of action, pause the pace in the middle, where characters mostly talk or walk or think or remember rather than doing action stuff, and build up to a big climax with faster pacing at the end.

It's a very popular structure. But now that everyone seems to have ADHD, it's being replaced by episodic structures which end each chapter with a cliff hanger.

Episodic structure isn't new, but quite a few savvy writers have discovered it's a better fit for ebook publishing than traditional long form.