Moon Phase Sprints

In Wicca there is a concept of the magical power of the moon. Each moon phase has different power, and different magickal workings should be done during each phase.  We can apply this to Agile sprints to make Moon Phase Sprints.  The sprints would be one moon cycle long (29 – 30 days).  The waxing half would be used for the generative, or creative, tasks, and the waning moon would be an opportunity for polishing, testing/fixing, and retrospective.  This gives an internal structure to each sprint, and lets the work follow a natural rhythm.