I hear this argument all the time and I don't buy it. Yes, my thinking is slower than 100 wpm on average, but it is extremely bursty. It goes at 0 wpm most of the time then 10000 wpm for short intervals.
I believe the fundamental concern here is not average speed, but latency. How fast can you get the current thought onto the page so that your brain can move on to think about the next thing?
I also type at 100 wpm, and I find my wetware CPU experiences stalled cycles while I'm typing, not able to continue because it needs to hold on to a buffer containing the thought I'm slowly typing out.
But, I expect it's diminishing returns on effort.
If you type 30WPM, you'll probably benefit yourself (and your colleagues!!) from learning to type quicker. 80 WPM seems reasonable; 100 WPM is good; 180 WPM is excellent. -- But, I think above some point, the costs of training to type quicker aren't justified by the benefits.
Are these benefits enough to make it the best thing in terms of ROI? I would suspect only rarely.
- If you're not yet at the point where you can understand what you're typing, you are probably served better by more traditional language learning activities. - If you do understand it perfectly you're probably at an advanced enough level that just reading it at your normal reading speed, or writing your own stuff and then having a native speaker is a better form of practice. - If you can understand it with effort but not at a comfortable reading speed yet - you're probably best served by throwing the individual sentences along with machine translations into a spaced repetition system like Anki. Then you can see the same sentence multiple times over the course of a few days and deepen your understanding a little more each time.