Most open source developers see planning as a boring task. Why plan if one can just go and code? The answer is as simple as the question: The "Go and code" approach does not let us create truly optimal code. Portions of code have to be changed while other portions are written. They often lead to redundant code or uninitialized variables, partially covered conditions, and wrong return results. Code gets a "do not touch" reputation because changing anything renders the whole project unstable. Often the code works, but the project is more a failure than a success because it cannot be extended or re-used.

Another reason for planning is the ease of bug fixing and the costs associated with it. Open source developers often do not think about it until they start selling their services or work to commercial companies.

As shown by recent studies, the cost of problem fixing grows rapidly toward the end of the project. The cost is minimal when development has not started yet...