The Amazon way appeals to me because in my experience pretty much no one ever does the pre-reading.

And even if they do chances are they've context switched enough since reading that most of the details are lost.

> At the other companies I've worked for, you were expected to come to the meeting having read the docs sent over email.

It may be expected but large numbers of people don't do it. The 20 min. thing is a bit odd but I can see how it could be a net positive.

Yeah, although the 20 minute reading seems better to me. For one thing, it means everyone in the meeting has actually read the docs. But it also means that it's fresh in everyone's mind when the meeting actually starts.