Re: Stopped reading at "command line tool" ...
When I say muscle memory, I'm talking about the ability to (in this case) press a key or combination of keys, without even having to engage the conscious mind. If you need to use a mouse to click on something, it may certainly be something you don't think about, but you *do* focus your mind simply be virtue of *having* to look where the mouse pointer is to click on something.
Things like walking, running or riding a bicycle are things that end up in muscle memory. GUIs certainly get easier once you are familiar with them, but I'm pretty certain that isn't quite muscle memory.
But... it's possible your (and other peoples) minds are wired different to mine.