So you start looking for more keys. I use Karabiner to turn capslock into command-alt-shift and fn-anything-but-a-function-key into command-shift. Or you make a keyboard with more keys - look up the "Space Cadet Keyboard" for a classic example. Or you get a couple of foot pedals.
(Foot pedals have other uses, too - transcriptionists have pedals designed to act as transport controls for the playback of the audio they're typing, so they never have to take their hands off the keyboard. I'm told they help speed things up a lot.)
You also don't necessarily have all those keyboard shortcuts memorized. But if you operate on a principle of "anything I need to do twice in ten minutes probably needs a shortcut so I can do it a ton faster next time I gotta do it a lot" it's easy to accumulate them, in any tool.
The office. Carpel tunnel is a PLAGUE for older engineers. We all have a ticking clock.
So for me a pedal is about saving my hands from stretching and mmoving and delegating that to a larger, stronger muscle/skeleton group.
>You never need to press 10 keyboard keys at once
https://en.wikipedia.org/wiki/Chorded_keyboard
Do you just hate everyone without 10 fingers? There's more than one reason to alter your keyboard setup.