A system that listens to a users journey around a web site could produce an almost unique experience. Would this be a more effective User Experience? Would this increase page views and ad revenue? If implemented properly, I think it could.
Generally, your interface designs wont be completely successful first time round. It’s not expected that you get it right first time. However, it is expected and far more important you understand your own design process should support iteration. That’s because iterating is the single most important factor in building a successful interface.