In my opinion, the most important phase is scope management plan. scope management plan is the collection of processes used to ensure that the project includes all the tasks required to complete the project while excluding all work which is out of scope. The Scope Management Plan details how the project scope will be defined, developed, and verified. This phase is the most important one because it would decide how is the design of the product looks like. A good scope management plan would make the products to match with the requirement of the customers. So it is very significant to decide to what kind of tasks should be included for satisfying requirements of the consumers for the product.