The first reason is the positive amplification. If someone connects you, you will show that you appreciate it. By linking them through websites as an article directory, you encourage them to do so in the future. Also, if the site linking to you is a quality site, you also accelerate the process of search engines matching the location with the site's quality. You help send more people to the quality site that connects you, creating more linker love to the quality site, which in turn strengthens the content of the links you receive.
Another reason is the Class C IP limit. I have never heard a definite answer to how it works, but you will apparently diversify that connects you. Let's say that the optimum amount is 5 of each website. When you have five links to a particular website, you will move to another website. But if you link the stack when you get a link from another site, you can send five links from the first website and so on.
Now you need to decide in which category your blog or site is located. Category A is a social blog or blog that makes money by being affiliated (or by selling your own e-book). Category B is a blog that makes money with Google AdSense.

If you are in category A, then you will stack as many links as possible to an article marketing site to generate more traffic. If your article occupies a prominent place in the search engine, it can appear on the most-sent page via email or multiple views that have many links. You want your article to be at the top of the stack of links (except your capital) and everything else in the bottom. If you are a social blog, you will generate more traffic or if your site sells something specifically, you will make more sales.
In Category B, you want to google stack as many links as possible to a site, such as Hubpages, so you can share the benefits of AdSense. If your targeted traffic moves to a site other than the page at the top of the pyramid, you will at least get some of the AdSense earnings if they click before you reach the top of the chain.
Another advantage of linking the stack is that it allows you to channel your juice to sites related to yours. Let's say your niche is the niche of weight loss, but you have several articles and centers for Make Money Online. You are in category B, so you want AdSense intersections to be close to the top. He has difficulty writing new weight-loss material, but he writes five Squidoo lenses related to weight loss. By linking your articles and centers that are not related to Squidoo before linking to your primary site, you strengthen the flow of links you get because you now get the love of links from a related site.
Let's say your reader is really into television programs. Start the reader in your article's catalog in an article on how good the TV is. It has two links in its author information, one for regular cable programs and one for premium cable programs. The reader clicks on the link similar to the regular cable programs. The reader arrives at his Hub and sees some messages about Basic Cable TV, but he is not really interested. Then you see that you have a Squidoo lens on the Flashforward TV show, then click on that link. Visit the site of your Flashforward TV show and watch ads on the forward-looking DVDs, but what you really want is a flashforward novelization, then click on your Flashforward novelizations site.
