A few hours in a row of hearing and typing C-Space C-u 2 4 M-w C-x C-b <RET> C-y C-x C-s is exhausting. It was also amusing (in retrospect) to get a polite-enough admonishment to "don't think about what the keystrokes are doing; please just type what I say" when he could tell that I was slowing down because I was paying too much attention to what the intent behind the keystrokes was.