I would also add that if I saw a file full of a million X's, I would not track each X as a distinct item in my mind, I would simplify the visual input down to "

I would also add that if I saw a file full of a million X's, I would not track each X as a distinct item in my mind, I would simplify the visual input down to "this is a file containing a lot of Xs" and work with that lightweight abstraction instead.