This depends on the financial stability of the company and how important the project you are working on is. If the project is critical and the time restraints are inflexible then going back to a previous phase would allocate resources that would otherwise be used to continue the implementation of the project. With regards to the posters statement ” Returning to the activities of an earlier phase doesn’t means you’re moving backwards or losing ground.It is simply means you’re incorporating new knowledge and information into the overall project plan.” I do not agree as the weight, cost, and amount of new information on the scope and feasibility of the project given the current understanding of the project can change drastically. If the new packaging that we are making is found to bind to a component on the device housed inside at high temperature, then defective products may increase post sterilization if done at high temperatures and can result in huge changes far beyond the initial assumption, and depending on how important the need for changing the packaging is, the project may be dropped entirely. If the changes are an additional label that needs to be added, then that can easily be incorporated into an existing designated task on the Gantt chart as the cost, both man power and time, is minimal even if the weight(importance) is high. Also if during the time you are going back to a previous phase tasked designated during the previous implementation phases are put on hold then you are definitely going to be behind. Or if tasks done are later deemed unnecessary then that is increased cost.