With all 12 practices in place, you’re reaping the full rewards of XP. New code is easier to write. New features are easier to add. Bug counts are down, and the few bugs that are introduced are easier to fix. Your customer is happy and you’re finding new enjoyment in your work.
That’s not the end of the story, though.
No development process can fully protect you from mistakes. The best it can do is to give you tools to prevent, identify, and adapt to crises. Of course, the same tools may help or hinder you from taking advantage of new opportunities. Your own experience and skills—honed and guided by a good process—are the best tools in your toolbox.
The real magic of XP comes when you take control of it. Your team has its own quirks and characteristics. Some are positive and some are negative. Tweak XP to your advantage. Maybe moving the last day of an iteration to Wednesday morning will give you time to react to immediate feedback before the weekend. Maybe adding a priority field to story cards will help the customer keep long-term milestones in mind. Always look for the next problem to solve.
Neither you nor your customers have to fear change anymore. Experiment. Find your biggest obstacle, solve it, and look for the next obstacle. Make little adjustments. Listen for feedback. You’ll be able to adapt to any situation.