Not just "peer code review" from a good friend or someone working on the same project as you - a review from somebody who has a ton of stuff to review at once, in many different areas, and very limited time to do it.
That's a pretty light annual workload. How do you get to be one of those people?
Or do those people have other work to do?
Yes, they have other work to do.
I'm pointing out that the number of papers someone reviews in a year is not even distantly related to the amount of attention they have available to devote to the job.