While it may be beneficial to have a broad communication management plan defined in an SOP, I think that communication management plans tailored to individual projects are more beneficial. This allows for the Project Manager to lay out exactly how the team members will receive the information that they need and how the details of the project will be communicated to upper management and the rest of the company. If the communication plan is already predefined in an SOP, the the PM is forced to follow the procedure which may result in a lot of unnecessary emails being sent spamming the inboxes of upper management. However with that said, it is crucial that the PM does not create a communication management plan where people are not getting adequate information about the project and any other associated details.