From Innovative Designs:
There is no absolute cookie-cutter design that a Web author or designer can apply to all possible communication needs. Why restrict freedom with rules that can hinder innovative design in the name of usability? Usability specialists and hypermedia experts would agree that you cannot design a Web site the same way you would a paper bound book. A book made of paper is organized and designed so that the reader absorbs the information in a linear fashion. The only exception is the non-linear structure of a paper-based reference text such as a dictionary. A table of contents, an index, and page numbers are peripheral elements used by the reader to help assimilate the information in a linear fashion. The dynamic content that is presented on the Web and the Internet, unlike the static pages of a book, gives authors and designers of this medium much more freedom in how information is delivered. Each visit to a Web site is a different experience.
Two visits on separate occasions by the same person to the same Web site can be unique because the content is dynamic. This ability of the site visitor to influence and control the content makes each experience distinct.
I constantly struggle with some of the design decisions while building web applications. Are the rules for a web application different from a web site? Familiar interaction patterns make the learning curve shorter.