Isaac Asimov took a 30ish year break between the original Foundation trilogy and the sequels/prequels. And I thought that was a long break!
As far as gaps go, I'm still hoping GRRM won't break any records
And I think that he will progress faster nowadays with the show. Not that I have high hopes for the series after book four and five.
I ask as a fan of The Expanse who has not jumped into GoT, and who wouldn't like to see The Expanse side-tracked because of it. Is there some piece of this relationship I'm not seeing, or is Ty Franck more involved in GoT writing than I would have expected?
http://www.tor.com/blogs/2013/11/george-rr-martin-no-more-ga...