I believe the first two books were released 4 years apart. It seems that that's the cadence for the books. And hey, Auri novella this fall! :D
See the article again: Patrick does not work for you.
I am also eagerly awaiting the third book but I want it to be as awesome as it can.
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I can't pretend to speak for Rothfuss, but what he's doing while folks wait for Kingkiller 3 looks pretty familiar to my own experience. I'm in the middle of writing and drawing the last volume of a trilogy of graphic novels. I'm constantly fighting to keep it from expanding into four books because I want to finish it around the end of the year; I have a list of things I need to make happen before the ending can make sense. And a list of things I'd love to take time to explore but a strong desire to not make the last volume twice the size of the first two together. And a very ambitious chopped-up timeline structure going on in the last volume.
And yet I've been spending the last month working on pretty much anything else besides this last book; my brain's been excited about a completely new idea for something I want to do about six years down the line (I already have long-brewing plans for my next story), I've been doing art for a convention, working on some short stories I promised. I have to fight myself tooth and nail to get any progress on this nearly finished story. Working on it involves loading a bunch of state into my head, and distilling it down into what is occasionally some very emotionally draining things to write; it is not an easy task. And every page I finish gets me one page closer to the ultra-complicated pages I'll have to draw for the climax, which in itself is pretty stressful - I'll be glad to draw them, but they'll be a ton of work, and I'm not 100% sure the idea I have will actually work, so I kinda want to just go off and do something... smaller. And simpler.
Endings are hard.
As an aside, I got restless recently and decided to reread the first two books. It really was a different experience the second time around, and I think well worth the time. This is one of those tightly interwoven tales where knowledge of the 'future' brings out details you never could have fully understood the first time around.
I started reading the Kingkiller Chronicle with the understanding that he had already finished the books, and would be releasing them each year for three years. Now that he's blown each deadline by a couple years, I'm a lil' salty.
Was I incorrect to infer some light social contract there?