Many of us who've ever been involved with a more-than-trivial project will have despaired at the waste of resources as the same lessons are learnt and forgotten over and over again. A crucial principle is one which should be attached to every project, PRINCE2 or not. This is the simple idea that the organisation should learn the lessons of previous projects and apply them, and also record and promulgate the lessons from the current project.
Project teams which aren't doing this can't really be said to be running a PRINCE2 project.
