XP teams produce quality software at a sustainable pace. Although XP is often presented as a list of practices, XP is not a finish line. You don't get better and better grades at doing XP until you finally receive the coveted gold star. XP is a starting line. The beginning of the answer is that if we want to leave software development uncluttered, we must be prepared to completely embrace the few practices we adopt.
Half measures leave problems unsolved to be addressed by further half measures.
Eventually you are surrounded by so many half measures that you can no longer see that the heart of the value programmers create comes from programming. The authors in the XP Series have been that and done there, and returned to tell their story. Excuse me, I gotta go program.