Throw Away

Plan to throw one away; you will, anyhow.

IN most projects, the first system built is barely usable. It maybe too slow, too big, or too awkward to use. There is no alternative but to start again, something but smarter, and build a redesigned version in which these problems are solved.

Accept the fact of change as a way of life, rather than an untoward and annoying exception. Nevertheless, some changes in objectives are inevitable, and it is better to be prepared for them than to assume that they won't come.

Plan the system for change: system which support version changes well.

Plan the organization for change: Each man must be assigned to jobs that broaden him, so that the whole force is technically flexible.

The changes after delivery are called program maintenance. These changes involve repair design defect, added functions which are visible to the user. The total cost of maintaining a widely used program is typically 40% or more of the cost developing it. The fundamental problem with program maintenance is that fixing a detect has a substantial (20-50%) chance of introducing another.

*quoted from Mythical Man-Month