Then just use 0.75 or 0.5x speed? I don't understand this question.

It isn't just how fast or slow it is. Reading at a slow pace gives you time to think in a way that is flexible from sentence to sentence.

To borrow the same analogy from the article, image trying to savor a meal where someone else was deciding when you take each bite. Even at a slow pace, the rigidness of the pace and your lack of fine control would still pose a problem with giving each bite it's rightful consideration.

That being said I love audio books and think I would struggle to apply this article's advice in my own life. Slowing down your audiobook is still a step in that direction, though I sometimes find that slowing it down can cause my mind to wander and my comprehension goes down and not up.

> Then just use 0.75 or 0.5x speed?

I think this often sounds unsettling (like the reader is drunk or otherwise impaired), and anyway the listener doesn't need more time to recognise each individual word -- they want time to take in sentences and paragraphs.