There have been a number of criticisms of the standard waterfall model, including Problems are not discovered until system testing. Requirements must be fixed before the system is designed — requirements evolution makes the development method unstable. Design and code work often turn up requirements inconsistencies, missing system components, and unexpected development needs. System performance cannot be tested until the system is almost coded; undercapacity may be difficult to correct. The standard waterfall model is associated with the failure or cancellation of a number of large systems. It can also be very expensive. — “The Standard Waterfall Model for Systems Development” Read more →