Am I Doing XP?
Don't expect a visit from the XP certification board. The fact is that there's no explicit metric to gauge your "XP conformance." If you're using the pick-and-mix approach with practices, don't expect to reap maximum benefits. In a recent experience, a developer claimed that he was "doing XP" because he was working on a project with no documentation and chaos ruled. That's not what XP is about! Review the 12 practices and keep applying. In the end, if you're not using XP but are getting results, does it matter? Pick a couple of practices and merge them into your own homegrown methodology. I won't tell, if you won't.