I think a catalog providing character synopses would be appropriate for most works of fiction.
Yes, that's another perfect one.
If you have ideas about information that would be useful to someone who is looking up the subject that you're writing about but that information doesn't fit comfortably into the flow of the main article, then it probably belongs in a subpage.
I'm still not sure that gives me a bright line test. Maybe we'll just have to follow Socrates, and say 'we may not have the perfect definition, but we have the example', and let it go at that. A list of all the existing subpage types might be a better 'definition' than any words we could come up with.
I'd say it's best to avoid creating subpages just for the sake of creating them.
True.
And speaking of the list of existing subpages, the procedure to add more subpages seem to have seized solid. There have been some good suggestions (e.g. Quotations, etc) but none have been added recently - something Petrea was exercised about (and rightly so, to some degree).
Noel