“TurboSEO” module improves your website’s relevance in search results as it informs search engine robot which pages have been updated and which not.
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As a matter of fact, module just tells search engine robot: "You “You already viewed it last time. There is nothing new. Come on, do not waste time and go to the next page."”
How does it work? When the crawler goes through the pages on your site a special tag with the date of last page visit is written to the page cache. So next time when the robot returns to the site it looks for this tag. If the tag exists the page will be ignored. In case the tag is missing the page will be checked for updates. The tag is deleted when the page is updated.
Thus, the search engine robot no longer needs to scan the same pages , as every time it revisits the site it checks updated pages, which improves your website indexation. Indeed, checking the "100 pages" “100 pages” and checking "100 “100 updated pages" pages” is a huge difference and advantage in Search Engine Optimization solutions.