I watched some order takers at a food service company a few years back. They worked in a green screen program -- not sure if it was DOS, or some terminal.

The speed at which they worked was unreal. Their hands never left the keyboard. They knew where everything was, and they could literally retrieve any information in less than one second, both due to the speed their fingers worked on the keyboard, and the responsiveness of the app.

I remember thinking that I need to pay more attention to keyboard-only usage of the next app I write.