This issue has cropped up in recent years with a lot of self-published authors; presumably they all use the same formatting program without changing the default options. Chapter headers have huge white spaces under them, usually 12-15 em, which can be more than 1/3 of the page. WHY is this necessary?
I always reduce those spaces to a more normal height with the calibre editor. But it's really annoying, especially in a book with lots of relatively short chapters.
I've attached an example.