So companies have to be very schizophrenic. On one hand, they have to maintain continuity of strategy. But they also have to be good at continuously improving.

wiley. Porter M. Criticisms
Porter has been criticized by some academics for inconsistent logical argument in his assertions.

Michael Eugene Porter (born May 23 1947) is the Bishop William Lawrence University Professor at Harvard Business School. Michael Porter’s work is recognized in many governments corporations and academic circles globally.