Stop doing code reviews and try these alternatives

In the "Knowledge Sharing" section of the article, the author says that "Distributed Practice" is one of the most effective ways to learn, and yet says that code reviews are not effective ways of knowledge sharing.

Isn't a code review EXACTLY a distributed practice? What am I missing?

And then he goes on to say "underlining and summarization while reading are least effective" -- I don't understand how is that even related to reviewing code.