No, they shouldn't. Many don't.
If there are any rules no one has told me.
A town meeting perhaps where residents gather and voice concern about the murder of another child. It's no longer a random murder and they have on their hands in their small quiet town, a child serial killer. Is it one of their own doing it, or someone they are not aware of. Several characters are introduced, some are kept and some are discarded and new ones brought in during the meeting.
Not a cliffhanger.
Now we return to the discovery in the woods.
You are right. Chapters know when to end themselves. Cliffhanger or no.