Keep Your Plan Up-to-date

You must plan a software project; however, having an out-of-date plan is even worse than having no plan at all. When you have no plan, you know you are out of control. When you have an out-of-date plan, you may naively think you are under control. So whenever circumstances change, update your plan. Such circumstances include changes to the requirements, a schedule slippage, a change in direction, finding excessive errors, or any deviation from the original conditions.

A well-written plan should enumerate the risks, the warning signs that the potential risk is becoming a threat, and contingency plans to put into place to reduce the threat. As a project progresses and predicted risks become threats, the contingency plans are implemented and the project plan is updated. The real challenge occurs when unforeseen changes occur. For these times, one often needs to replan the remainder of a project in its entirety, with new assumptions, new risks, new contingency plans, new schedules, new milestones, and so on.

Reference:

Reifer, D., "The Nature of Software Management: A Primer," Tutorial: Software Management, Washington, DC: IEEE Computer Society Press, 1986.