Comment by laserbeam

The statistic is actually wrong, I misremembered. It is from Tantacrul, a designer overseeing the current design of MuseScore and the redesign of Audacity. It's a finding he had while working at microsoft on a revamped version of MS Paint (the man has since moved to greener pastures).

The actual moment is a few minutes into the section about shortcuts (of a long video trashing a piece of discontinued music software). The actual bit was that undo/redo was the most clicked button in the MS Paint interface, and that people overwhelmingly prefer the button over the shortcut. No actual number is specified.

https://youtu.be/Yqaon6YHzaU?si=uDFFQgrbZuYFifhS&t=1580

The correct statistic (which I associated with the other example in my mind) was that only 17% of users use more than 20 shortcuts.