Google recently updated their patent on software that analyzes page hierarchies and URL structures. This suggests that page hierarchy will continue to be a factor in SEO for the foreseeable future. There are a few reasons to give your site a clear page hierarchy and structure. First, it makes the user experience better for people. Second, it makes it easier for bots to crawl your site and quickly grasp what the content is about. Last, it ensures that you will get more site links on google. That is, underneath the link to your page in search engine results will be several links to different category pages.
How can great page hierarchy be accomplished? Make a flow chart or outline. Group like pages under a single category and give each category a landing page that links to the subpages. Try to maintain shallow depth, which means that every page on your website can be accessed within three clicks.