Except that there is no "standard speed" for speech, let alone one that we've been using across cultures and languages for "millennia." People speak at different speeds depending on many factors from personal idiosyncrasies to emotions to a desire to hit a specific timing (it's not an accident that radio presenters get exactly the same time every time; they modulate the speed at which they are reading depending on the density of the information they have to deliver). Lectures, in particular, are often intentionally delivered in an unnaturally slow pace, which makes sense for maximizing comprehension, but means the pace may be very, very slow for someone who wishes to review mostly-familiar material. The idea that it's impossible to follow a lecture sped-up under any circumstances is just not at all in accord with my experience.