Project management is heavily reliant on successful planning, and the Planning Process Group is an integral part of descriptive development approaches and lifecycles. Do not confuse it with the planning performance domain in the PMBOK 7.
However, the rise of agile development approaches has led to the introduction of project management principles and system for value delivery to replace process groups. Furthermore, knowledge areas are substituted by performance domains and tailoring processes as part of the project's body of knowledge. To be sure, process groups still play a major role in predictive lifecycles, but the importance of the planning performance domain cannot be understated.
Once the Initiating Processes have been finalized, the Planning Process Group comes into play, allowing us to go into further detail. It comprises processes that create instructions to execute project goals and tasks within the project's scope, while also determining the best course of action to reach said goals. Therefore, the Planning Process Group is an indispensable component of project management, not just in the form of exam preparation, but also as a key element of the entire project management approach. In other words, a project's success should always be premeditated.