There is no discussion – subheads fits well on a stories that needs to run long.
It, even, looks very effective, not only do they break the story but also allow writers to hint to the readers what follows in particular part of the text.
How to effectively use subheads:
Use a type least one point bigger than the basic text.
Make a little white space above subheads to highlight them.
Serif and sans serif are fine for subheads.