The third phase in Cambridge's CoRAD methodology is the product design stage. The emphasis during this six to twelve week phase is on architecture. The technologists architect an infrastructure for your product that is secure, scalable, and reliable. The creative and cognitive designers build on the work begun in the prototype to architect a powerful and effective user interface for the customer. A good rule of thumb for web applications is they should be so simple to use that no help screens are required. While this may seem limiting, it is indeed true. PeopleSoft, for example, a popular vendor of enterprise resource planning applications, has designed all its web-deployed interfaces without help screens. Also during this phase, the business consultants architect new processes and organizations to align the functionality in the application with the delivery capabilities of the organization. Customer testing of the prototype also continues during this phase, allowing additional feedback to be gathered and incorporated into the evolving design.