I think a lot of people mistake "cause" and "effect".
From Google News (publishers) Help area:
"From the moment we discover a new article, we'll keep re-crawling it looking for changes. Since we've noticed that most changes to articles occur just after they're published, we revisit articles most frequently in the first day after we've found them. After that, we visit them less often."
Effect: authority news site's "freshened" content gets a bump.
No "talented" SEO staff required.
Google does it as part of the (totally automated) News algo.
I find most of the bigger regional news outlets publish many stories at 12:01am - 12:05am with very skimpy details. Throughout the night and early morning they add to the articles... bump, bump, bump...
If they plan to do a follow-up article on a new angle or in-depth coverage, they hold it until after 11:59:59 that night, so they can start with a new story for a fresh crack at top of the heap.