As you point out, there's a tension between a methodology that cannot fail--only be failed--because in practice it is impossible to use and yet the need to actu

As you point out, there's a tension between a methodology that cannot fail--only be failed--because in practice it is impossible to use and yet the need to actually do things the methodology says if you want to really test it. XP, being a very high discipline methodology, is particularly vulnerable to this; the literature is full of people who claim to have tried it and when you press them they threw out all the parts that make it work, and this post was born of Jeffries' irritation by this. Whether it is possible for other teams to actually pull XP off is harder to say.