I asked around and found this practice is far from rare; I'm not sure
"common" is the right word, though.

You really need to type if you run cw over about 60wpm
or so.. That was about my limit as far as sending fairly clean
with a paddle. I never liked to type, so 55-60 wpm pretty much was
the limit for me. Most all the high speed people used a keyboard
to send. But I'd say the majority listened with their ears instead
of using a reader. The brain is a better reader than most puter CW
programs. Most don't handle noise very well. Once I hit 55-60 wpm
on a paddle, I was stretching the limits. Past that, and it was pretty
dang ugly... Slopsville. The keyboards could kick back and type
about any CW speed with perfect sending. A decent typist can go
over 100 wpm+.
MK