I don’t know much about Cory Doctorow, but I like some of the writing advice he gives:
Don’t research. Researching isn’t writing and vice-versa. When you come to a factual matter that you could google in a matter of seconds, don’t. Don’t give in and look up the length of the Brooklyn Bridge, the population of Rhode Island, or the distance to the Sun. That way lies distraction — an endless click-trance that will turn your 20 minutes of composing into a half-day’s idyll through the web. Instead, do what journalists do: type “TK” where your fact should go, as in “The Brooklyn bridge, all TK feet of it, sailed into the air like a kite.” “TK” appears in very few English words (the one I get tripped up on is “Atkins”) so a quick search through your document for “TK” will tell you whether you have any fact-checking to do afterwards. And your editor and copyeditor will recognize it if you miss it and bring it to your attention.
When he talks about writing in twenty minute bursts, I assume he’s thinking of multiple bursts during the day, but here is a link to the original article so you can decide.