I believe you could consume all the words in Moby Dick in 16 hours. But it’s one of those “crammed full of metaphors” books that could easily take a seminar to unpack. I don’t pretend to get it, but smarter people than me write articles on its layers of complexity and interpretation[1].
You can read those masterworks at a superficial level and they’re usually somewhat rewarding. Or you can read Dostoyevsky while deep diving on Russian history and get a notably different experience. But it takes a lot longer.
I generally read audiobooks at 1.5x because 1.0 seems terribly slow to me. This more or less matches my reading pace for printed books, so 16 hours seems right.
Not everyone is native English speaker, and slow pace allows you to get immersed. That people want 1,5 speed or do two things at same time is a sign of our time (appropriate content is cheap snd widely available but we don't have more available leisure time). Society doesn't want people have abundant leisure time, hence 'Bullshit Jobs'.
I'm not a native English speaker either. The thing here is that audiobooks are quite a bit slower than normal speech, which is what we've been trained on all our lives.
People want 1.5 speed because that's what gets the narrator back to a normal speaking speed.
I slow down some narrators and speed up others because I like content delivered at a specific speed. Leisure time is a reason, but not the only reason.
https://www.audible.ca/pd/Moby-Dick-Audiobook/B071NYW4Q1