Back at the Philadelphia Worldcon (which seems a million years ago), I announced the famous five-year gap: I was going to skip five years forward in the story, to allow some of the younger characters to grow older and the dragons to grow larger, and for various other reasons. I started out writing on that basis in 2001, and it worked very well for some of my myriad characters but not at all for others, because you can't just have nothing happen for five years. If things do happen you have to write flashbacks, a lot of internal retrospection, and that's not a good way to present it. I struggled with that essentially wrong direction for about a year before finally throwing it out, realizing there had to be another interim book. That became , where the action is pretty much continuous from the preceding book. Even so, that only accounts for one year. Why the four after that? I don't know, except that this was a very tough book to write -- and it remains so, because I've only finished half. Going in, I thought I could do something about the length of the second book in the series, , roughly 1,200 pages in manuscript. But I passed that and there was a lot more to write. Then I passed the length of the third book, , which was something like 1,500 pages in manuscript and gave my publishers all around the world lots of production problems. I didn't really want to make any cuts because I had this huge story to tell. We started thinking about dividing it in two and doing it as , Parts One and Two, but the more I thought about that the more I really did not like it. Part One would have had no resolution whatsoever for 18 viewpoint characters and their 18 stories. Of course this is all part of a huge megaseries so there is not a complete resolution yet in any of the volumes, but I try to give a certain sense of completion at the end of each volume -- that a movement of the symphony has wrapped up, so to speak.
George R. R. Martin