Many people own many different websites and the question is how much interlinking on the sites they can do? How can they connect one website with another without getting penalized?
You want to be careful going crazy with interlinking. Through Analitycs or Webmaster tools but also emails and even blog sites Google knows what websites you own. Unless you are very careful. Interlinking is more helpful if you think about the people not the search engines. Try to find pages that are relevant and link only those. Don’t use unrelated links on your pages if it doesn’t match your website. For example if you have a website about Traveling, don’t link it to your alternative diet blog. Link something along the lines regarding Africa.
Irrelevant Footer and sidebar links are also not the way to go. First of your visitors won’t understand why you have irrelevant links on your websites and the search engines are also ignore it.