As someone who designs websites as a (big) part of his job, I don’t believe that, in most cases, a wholesale redesign of a live website is necessary. Many times, a gradual evolution in design and navigation is preferable, particularly if your site is highly trafficked and profitable. Not to mention a large part of their users’ lives. Look at Yahoo and Amazon, two sites that have seemingly changed very little over time; new features get added, new home page elements appear and are integrated without much disruption. In a …