Every next framework activity behaves according to the tasks implemented on its previous activity. For example, you will code what have you designed.
If one activity is not reviewed and if we proceed to next activity, tasks which are missed in previous activity won’t be implemented in the next activity and so on.
Let’s take an example of the first activity of Software Development Life Cycle where all the requirements are communicated and documented. Yet, if there is no reviewing, and some functionalities are misunderstood, then unwanted functionalities will be planned, designed and developed. Instead, if there was a review on the requirement specification document, this mistake would have been highlighted and solved at the initial phase. Similarly, if communication and requirement specification is done in proper but if there occur some mistakes during planning activity, it will harm the next process. Thus, reviewing all the activities are important.
Thus, reviewing all the activities in software development life cycle are important.