I've been playing stringed instruments for more than 10 years. The 'e' 'x' combination is probably the most spastic and slowest key combination on a qwerty keyboard. I type about 100 WPM, so typing exa doesn't take _that_ long. But it feels like it's at least 5 times slower than typing ls. Which would be really annoying for a command that you'd be typing all day.