As a result, I don't think anyone would call my writing practice "structured." Far more than I'd like, I work in boom and bust cycles. My only saving grace is that once I'm cooking with a draft, I'm almost entirely lost to the work. I'm pretty good at being obsessed.
As for your question about being blocked, the answer is: Yes, I did reach a point where I was stopped cold. I had written half of a first draft of The Story of Edgar Sawtelle. That draft was narrated by Edgar directly, in first person point of view, using a retrospective tone. By the time I'd reached the beginning of Part 3, I just could not bring myself to continue writing. Something was wrong, but I didn't know what, and my imagination seized up. I set the book aside for more than a year. Because I didn't know why the well had gone dry, I starting thinking maybe the whole thing was just wrongheaded. I would go back to Part 3 once a week or so and see if the passing of time had made the problem magically disappear, but as soon as I tried to write new prose in Edgar's voice, things ground to a halt again. As you can imagine, this was not a recipe for a happy life. Eventually, I decided I was either going to have to throw myself at the problem or give up the book for good. I resigned my job, making two promises to myself: (1) I would have exactly 12 months to get a draft completed and revised, and (2) there would be no wriggling out of the work, no matter how hard it turned out to be, because I sensed I was never going to write another book unless this one was completed, even if it turned out to be a bust. The first promise was easy to keep—I knew I'd be out of money after a year. The second was much harder, and I decided to address it by breaking the work down into less daunting assignments.
My first assignment was to read what I had from start to finish. Not pleasant: first draft is inevitably rough. My second assignment was to switch the point of view. I went through the manuscript and converted the narrative from first person to third person, page by page. This was tedious, but not especially difficult. By the time I'd finished, I understood why I'd been blocked: remaining strictly within Edgar's point of view, using his "voice" to tell the story, was simply too constricting—certain events needed to be seen from outside Edgar's experience. I noticed again and again how much more freedom the third person point of view afforded me, both in diction and in perspective. Looking back on it now, I feel I should have understood this all along. In fact, even before I got stuck, I had written the first of Almondine's chapters as an experiment, and I liked it. So I had already departed from a strict first person point of view. But I had been forcing my idea of the storytelling onto the material rather than listening to what the material needed and had gotten myself into one of those immovable object vs. irresistible force situations.
Once the point of view was switched, I finished an enormous, rambling first draft in about nine months and a slightly more focused second draft about six months after that (and going back to work in the meantime). I revised the whole book several more times (we're talking years, here) before I finally began submitting it to agents for literary representation. And of course, it was revised several times yet again working with my editor at Ecco Press.