Matt Cutts, Google’s liaison with the SEO industry, released a video where he offers some insight regarding Google’s Freshness Updates and how they affect rank positions.
The Freshness Updates have been misinterpreted by many in the SEO industry as a mandate to continually provide new content updates, even if the content is not specifically targeted toward the primary focus of a web site. This never did make any sense to me and I never saw any effect from adding a blog to a site when the content in the blog was either syndicated or unrelated to the site’s primary business.
Part of the problem is that Google has never clarified the issue of fresh content in the past. They formally started to release Freshness Updates in November of 2011. Freshness Updates were believed to seek out the newest content related to a search topic.
Matt now says that a site does not get a boost simply because of new content. The topic of the search itself determines whether or not fresh content matters, and determines whether or not the search is a QDF (query that deserves freshness) query. Those are mostly current events, breaking news, major new product introduction announcements, etc.
Matt also clarifies that simply periodically altering content does not necessarily result in a ranking boost. From my experience, it does help to periodically review the content pages in a site simply to assure that the content is not getting old and obsolete. It is also a good idea to assure that all of your pages are focused on your targeted keyword themes. Straying too much from your core keyword themes can have a dilutive effect on rankings over time.