My first novel, Hudud and Escape, was written during NaNoWriMo. My Second, Jihad and Unheard, was started during one NaNoWriMo, supplemented throughout the following year and completed in the following NaNoWriMo. I have the write the concluding part of the trilogy now and plan to make a proper start on it this November. If I don't, I'll never hear the end of it from my readers, kind of left it on a cliffhanger. Whoops.