If it fails to meet them all, the process will begin again to develop the needed enhancements. The most common pre-RAD methodology is called the waterfall method. In this model, each step of the application design and development process is completed sequentially. The needs assessment is performed and completed. Next, the system is designed.
Development starts only when the design is locked down.
When development is completed, testing begins. Only when all testing is completed is the system reviewed. RAD collapses these discrete phases into one continuous process. RAD techniques shorten the development life cycle, but that's not all they do. By bringing the end users of systems together with the developers early in the systems development process, RAD helps ensure that the final product meets the real-world business needs of the organization.