Everybody has certain behavioral habits. You can gain a competitive advantage over your competitors, if you can discover and include your users' behavioral habits into the usability of your site.
Examples of Web User Habits:
Most people scan Web pages
Some Internet users nearly always head straight for a site's search form to find what they are looking for
Some users like to open hyperlinks to new Web sites in a new browser window, so they can continue reading the current page, while the new Web site is downloading in a separate window