Have you read the New Yorker article on GRRM? It was an interesting combination of several things, including bothersome media topoi about fans and about fantasy/genre fiction, but it did leave me thinking about the production pace of those books, and what's reasonable to expect, or not.

As much as GRRM or any writer is not anyone's bitch, I do think at some point, after several years, the question of production pace/work ethic does become legitimate to raise.