Why We Buy suggests an alternative approach. There's plenty of opinion about what makes for good website design, but little that I have seen treats what we could call the route characteristics of user interaction. Good website design tends to stress usability of information resources, and looks at layout, sectioning and signage. But a purchase transaction is the outcome of a series of interactions that itself describes a route through layers of pages, each layer marking a stage in the business process. The route taken by a user may be one of many possible routes afforded by the site's design.
Many sites contain routes that loop, continually whisking users away from the outcome they seek.
In some sites it's possible to fill your shopping cart but hard to see the checkout. Most of the time the checkout will be there, but just not noticed or registered by the user. The parallels with the physical retail world start to become clearer. The wisdom of physical stores is that aisles contain products, and checkouts are sited at exits or traffic nodes. Yet the reality in physical stores is that sometimes checkouts are obscured, or marooned by informal traffic diversions generated by the siting of promotional displays.