Small Iterations of Software

A development "cycle" in XP can be between 1 - 4 weeks, often 2 weeks for many projects. That would seem to put a lot of extra overhead into the process and be too short a time to get anything meaningful developed. Of course, it all depends on your definition of "meaningful." XP defines meaningful development as the completion, and stakeholder acceptance, of one or more user stories. There is additional overhead, but there is also continual forward progress on the realizing the product goals. Very short planning cycles allow significant flexibility in changing priorities (as in which user stories to do next) without derailing the engineering process. It also provide feedback about the overall velocity of the project. (Anyone who has observed first-hand the devastating effect on the productivity of a traditional software development process when plans or priorities change will understand this point).