Why some websites get more of traffic and some don’t—the 80/20 rule.
You wouldn’t need a 25% increase in time on site to get Google to increase your page rank and send you more traffic, just a tiny advantage would do the trick. Google wants their customers, the people using the Google search engine, to be happy with their search results so customers don’t switch to another search engine. Google is going to reward sites that have a little extra something special with more traffic because it’s in their best interest to do so.