A rare concept to methodologists.

CrystalClearMethodology explicitly calls for it, and I think XP implicitly demands it, but most methodologies try to minimize the need for it.
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The biggest problem with this concept, and I think I'm serious here, is that it disqualifies so many from participating. --RonJeffries

''...and therefore the need for it should be minimized?''
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For a disagreeing view, see DontUseYourCommonSense