Ironically enough your example is flawed: there are documented 10x touch-typists.
The realities of the court system place high demands on the typists; the minimum required typing speed is already quite high: trained court reporter or closed captioner must write speeds of approximately 180, 200, and 225 words per minute (wpm) at very high accuracy in the categories of literary, jury charge, and testimony, respectively[1] - and some exceed the minimum and go for 300 wpm. Even better, the official record for American English [is] 375 wpm [2].
Compare that to the average typing speeds around 30 - 40 wpm [3] Granted, the court reporters use specialized input devices (stenotypes) - but hey, the same can be said about highly productive programmers, who use specialized development environments - and sometimes also specialized input devices.
You make a good point that hints at another often-undefined assumption in these discussions - 10X performance vs who, exactly? IMO, it should be vs "a typical peer in that profession". For court reporters, if "a typical peer" is a trained court reporter who averages ~200 wpm, and a superstar is at 300wpm, then it's a 1.5X gain. If a "typical peer" is a regular Joe, then 300wpm would be 10X - but this doesn't feel appropriate because we compare productivity of a "10x developer" vs a "typical developer", rather than vs "an average Facebook visitor".
Ironically enough your example is flawed: there are documented 10x touch-typists.
The realities of the court system place high demands on the typists; the minimum required typing speed is already quite high: trained court reporter or closed captioner must write speeds of approximately 180, 200, and 225 words per minute (wpm) at very high accuracy in the categories of literary, jury charge, and testimony, respectively[1] - and some exceed the minimum and go for 300 wpm. Even better, the official record for American English [is] 375 wpm [2].
Compare that to the average typing speeds around 30 - 40 wpm [3] Granted, the court reporters use specialized input devices (stenotypes) - but hey, the same can be said about highly productive programmers, who use specialized development environments - and sometimes also specialized input devices.
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[1] https://en.wikipedia.org/wiki/Stenotype
[2] ibid.
[3] https://en.wikipedia.org/wiki/Touch_typing#Speed