It's fair to say that authors have been creating some mesmerising worlds – so mesmerising that they find themselves unable to pull away and end up writing several novels about the same characters and/or settings.
But this isn't anything new. Just ask the comedic master himself, P.G. Wodehouse. I recently purchased a copy of Blandings Castle, and had to share the beginning of the preface – there will be many authors that will chuckle at these words of truth!