There should be periodic review of strategy to find out whether the given strategy is relevant. This is required because even the care-fully developed strategies might cease to be suitable if events change, knowledge becomes more clear, or it appears that the environment will not be as originally thought. Thus, strategies should be reviewed from time to time. What should be the frequency for such a review is not universal but major strategies should be reviewed at least once a year. In fact this is done by most of the organizations who believe in relating themselves with the environment.