I think 3x is the wrong target here, it's the learning by listening model aka "The Nurnberg Funnel" (or possibly Nuremberg Funnel for German speakers) that is harmful.

I'd rather have a more focused lecture at 1x speed, the same as I'd rather have a good textbook, but skimming in both cases is fine if you want some info but the presentation available is too simple for you.

But, learning by doing and finding out what you don't know by doing is important. That applies even to crappy end of chapter multiple choice quizzes or whatever their audiobook equivalent is, but I find project based learning to be where it's at for really cementing knowledge without boredom.

edit to add: I'm not sure about the bit about pre-textbook lectures is historically accurate. I was under the impression the modern lecture mostly derived from the time when books were expensive, non-mass produced tech and the single copy was chained to the lectern and the person reading it out was doing so in order to let people make their own cheap copies.

I'm a big fan of video lectures that people consume in their own time, but more because they can slow them down, and rewind, not because they can speed them up. If you're always speeding up, you could probably just get a denser text