"Dear Ed, you've written lots of novels and nonfiction books. Do you ever experience writer's block?"
The short answer is no. I certainly do go through periods when I am distracted by other things, real-life concerns that divert time, energy and focus from writing. Once I am in my "writing mode", however, I usually work pretty fast. Not Isaac Asimov fast, mind you (Asimov sometimes completed a novel in a few days); but reasonably fast: I can write 2,000 to 3,000 words per day without sacrificing quality or frying my brain cells.
I can't understand full-time, working writers who need three, or four, or ten years to complete a 300-page novel. But there are plenty of them. Richard Ford, a novelist whose work I enjoy, has been a working, published author since 1976, some 37 years. Since then, he's published seven novels and four short story collections--a total of 11 books.
That comes out to 3.36 years per book. (And Richard Ford's books are not particularly long). This would be a very respectable pace for a part-time, weekend-and-evening writer. For a full-time writer, though, it seems kind of slow, especially when compared to some genre writers who crank out several books per year.
Speaking of the part-time writer: I can, of course, understand part-time writers who require multiple years to write relatively short works, who have to squeeze writing time in between the demands of jobs, spouses, children, and other commitments. I can also understand how it can take years to write a thick nonfiction book. Research takes time. Organizing a vast amount of research into a coherent text takes even more time.
Usually when a writer has what is commonly referred to "writer's block", the problem is a lack of preparation on the front end. This means that he or she doesn't fully understand what needs to be written.
The error here is a lack of what I call pre-work: Before you sit down to write anything--be it an email at the office, or a 500-page novel--you need to plan.
The amount of required planning varies, depending on the nature and length of the piece to be written. For me the planning stage sometimes occurs entirely in my head. Or it might consist of a few notes jotted down on a legal pad, or typed on my iPad. Alternatively, the planning stage might involve an elaborate outline. (I have written outlines as long as 5,000 words before starting to write a book.)
But the writer (and I use that term generically here) should always plan before attempting to compose. It's generally a bad idea to attempt to combine the planning and rough draft phases. When you try to plan while composing a rough draft, you are forcing yourself to plan what you want to say, while thinking about how you need to say it.
This usually results in a condition in which the writing process feels excessively difficult--a condition known as "writer's block".