The Site Overlay/Next Click Analysis is an important analysis that can be carried out to understand how the users are using the site navigation to find their way around from the landing page. This Next Click /Site Overlay analysis is very essential to understand how easy or hard it is for users on you site to reach the final goal : in case of a ecommerce site it can be the checkout page, in case of a content site it can be a lead submission page or registration page. It's not as important in case of blogs, but still can play an important role in helping to decide where to place the links to other posts.