I should post links to these pages systematically on the new different blogs and see if there is a traffic increase.
If this works, it means that search engines pick up not only the new blog posts on an established blog, they are happy to pick up as well older well established pages with no blogging interest.
Let's check that.
The best way to do that is to post links to the first series of extra4 pages - that's around 60 SEO pages.
Do that systematically for 3 days and see if traffic to these pages does increase or not.
Remember that with the blog posts, traffic increase can already be seen within a few days.
That's pretty fast!