In a recent John Mueller hangout, an SEO professional asked about footer links on multiple sites.
They have several sites from the same owner. These sites discuss different topics, but all fall under the same banner of gaming.
So basically, these sites all talk about different aspects of gaming, and the SEO professional wants to link between these sites in the footer.
They were also concerned about whether this tactic violated Google’s Webmaster Guidelines.
John Mueller explained that so long as you don’t have 500 sites that you’re doing this with, you should be fine.
He recommends that you keep the sites to a reasonable number, say between 5 and 10.
He also said that it’s possible that if you take several sites and shrink them down into one site, you could become a very strong competitor in that industry.
This method is better overall, rather than creating multiple sites that all link to one another, because you’re maximizing the strength of one site.
This happens at approximately the 41:40 mark in the video.