Well, we employ project management processes in every project. Simply this is to increase the quality of our work, have a more predictable outcome for our project. More complex is your project, the more attention you need to pay to these processes.
If you believe that the passing the PMP exam can be treated as a project, then you can only increase your chance of passing this exam by following project management processes. You can read the full details about this approach on the paper listed below.