What about pausing when the writing gets hard? Ah; this is a place for nice judgment and some brain science.
When a mental project such as solving a puzzle or overcoming a design challenge becomes difficult, there are two options: push through, or take a break to allow your unconscious to gnaw on the problem without your pesky conscious mind interfering.
How does one know when to do which?
In Jonah Lehrer’s Imagine he points to research which gives us an answer. If you’re making progress, however slight, keep pushing. Any forward movement is a sign to keep at it.
When you’re well and truly stuck, though, further bashing against the bricks is fruitless. This is the time to get your conscious mind off the project and hand it off to the rest of your brain.
If that sounds like assigning a task to an assistant, that’s exactly what it is. Do it literally. Tell your unconscious (out loud, if you’re brave enough or desperate enough) “I’m taking a break from this for a while. Please work on [clearly stated challenge] while I’m away so you can provide a solution when I come back.”
Then, go away. Do anything else in the world. Keep your brain occupied elsewhere. Might be a good time to reconnect with those other human beings who live in your house (I love the sign one friend had on her wall: “Who are these people and why do the keep calling me ‘Mom’?”) Physical activity is good. One doctor called the physical benefits of exercise “peripheral” because the benefits to the brain are so significant. Just remember to keep your conscious brain off the problem. Your unconscious is on task now. Stay out of its way.
Here’s the part you won’t believe until you’ve tried this more than once: at some point, your unconscious will serve up the answer. Once in a while the clock will run out on your break before that happens, but when you sit down to write, the challenge will vanish. Words will flow. The solution will be so obvious you’ll doubt it ever existed. (Journaling is your friend. Writing down when, where, how, and why you’re stuck will give you some perspective when these “obvious” solutions present themselves.)
Your unconscious works non-stop. It’s how you breathe while you’re asleep. It pumps your heart a zillion times during your life. You have no idea of its power.
Use it. Stay out of its way while you take a break, and watch it work.