3 WPM really shook me as well. Today we complain about not having enough time to work on our projects, but back in the good old days, as successful as Dijkstra was, got time to spend 3 WPM and still produced close to 7k articles! Astonishing.
Human thought speed seems to be a reflection on how fast you need to think for normal conversations. Thus orders like "run" or "jump" are likely to be fast as if you need to tell someone to escape a lion speed is important. While if you are planning a hunt you are allowed a lot more time to get details right. Engineering often is a very slow activity as you need to think about a lot of details but you have time. Typing a message like this I want to be fast enough to follow my thought speed which is much faster (I won't claim to type this fast, but I get close and can believe with more practice I would be this fast)
When corresponding, I type at around 120 wpm. When coding, it's got to be closer to 5 or 10. But I really like this idea that it would be useful to push that number lower (while still focusing on the task at hand).
Thing is, I got into this field because I really enjoy interacting with computers via keyboard. It's super satisfying to punch some buttons and make things happen. This is what I love about vim: right off the bat, a single button press feels like it does a lot. Then you punch a whole bunch of buttons to make a new button make something happen. Nevermind that it doesn't achieve product goals. I'm here for the button pressing, and for the creating of new buttons to be pressed.
I can type at >100 WPM (just tested). I recently had to write a 3-page document for work, the summary of weeks of research and interviewing. It wound up 1959 words (just checked). I wrote it over the course of one 8 hour day, after having procrastinated on it for the previous 2 days.
I came home at the end of that day exhausted because I felt like I finally did weeks of work in one day.
But, this 8 hour day had 2 hours of meetings and 1 hour for lunch. Say another 1 hour for random slacking. So pure concentrated writing was 4 hours or 240 minutes, which winds up to about 8 words per minute. That's it!
And I would consider this fairly fast, and again I'm not including the 2 days where I tried to write the doc at various times but failed to get started. SOMETHING was spinning in my brain in the background getting the ideas clarity.
Writing with a pen I tried, but no-one, including me, can read it after...
I don't know about anybody else, but I spend 8-18 hours a day attached to a mouse and keyboard. I'm not going to use one that doesn't feel good to me.
Buying nice peripherals is like buying nice clothes.
Perhaps some people just really need to take that to extremes, getting out of their head all their fragmentary or preliminary thoughts, and filtering and working them down on paper or the screen?
It generally seems (to me) that a good-heavy amount of thinking first works best and/or is most productive, but overall, we all have different brains, training, and experiences, so I'd go with: "whatever works for you" (but try multiple methods).
And we're talking journalistic opinion piece, which are a dime a dozen, not deeply nuanced scientific writing. If anything Dijkstra was writing his notes too fast and loose!