Here's a thought experiment. Sit down in the morning with a cup of coffee and a list of topics. Work through them, one at a time, coming up with and writing down 500 words or so on each topic. How many topics do you get to over the course of the day, and how long does it take you to write 500 words that make sense? Assume for the sake of argument that there's a typical number of distracting email, Twitter, and Facebook posts that you have to deal with. Each of the pieces that you are writing will need to contemplate a part of the net that might lead to its own distractions.
I am always impressed by people who have the ability to sit down and crank out clean copy that is ready for publication. It's not by any means easy to do this, and certainly every written work can be improved by judicious editing. I'm thinking more of the remarkable skill where you can type as fast as you can for a short burst and have the resulting words make sense, flow nicely, and be worth posting to the world.
The practice I get doing this has a lot to do with blogging, where I want to capture the moment and some momentarily interesting topic and put my mark on it. This is not writing a novel, and not writing a little piece of a 20-page or 400-page non-fiction work; rather, it's somewhere between journalism and blogging. The work you are composing is temporarily interesting to a number of people in part because it has a good headline for Twitter and a body full of words that search engines like. You've written news, but it's within the context of a blog, and because of that it's perfectly acceptable to leave questions unanswered and stories unresolved. It's what musician Michelle Shocked called the "incomplete image", and perhaps you are waiting for someone with a longer deadline to write up the full story.
I know from experience that I can put together 500 words in a sitting on one topic without taking a break and without needing to consult an outline. The much more challenging part is making a long, coherent single narrative out of these intermediate pieces parts. The skill of impromptu essay writing is by no means the same as the skill of book writing, and the task of challenging yourself to come up with a story that moves the current understanding a bit forward is a challenge.
To some degree, I'm willing to pad out those words with ample quotations from other sources, a sort of journalistic cut-and-paste that sifts through less well known sources to string together a story. (Of course the excerpts are carefully hyperlinked to avoid any suggestion of use without attribution.) Careful reuse of existing copy is one of the qualities that blogging can take advantage of that isn't generally OK in journalism circles.
If all you wrote were impromptu essays for the net, you'd quickly find out what was a keeper by the traffic you were able to draw in. On a good day, I'm happy to write three or four blog posts that either satisfy my own interest in preserving a bit of news or that advance some larger story or that answer a question that's on more than one person's mind right now. That would translate into 2000 words on a good day, and that doesn't sound like a lot. I think you'd have to work hard to keep the hopper full of article ideas and to keep up the research that fed a constant stream of ideas to work from, and to work doubly hard to collect the sort of essay-sized chunks that would eventually tell a story that's longer and more carefully planned.
(Inspired by #writechat on Sunday, 8 December 2013.)