Hi Riaz.
Organizational process assets (OPAs) are the plans, processes, policies, procedures, and knowledge bases specific to and used by the performing organization. These assets influence the management of the project. (PMBOK 6th Edition Pg 39) It is from these OPA's that we draw up the business case and subsequently the benefits management plan. It is therefore likely that the business case and the benefits management plan can become part of an organizations OPA's and more so if the project is successful.
Subsequent projects within the organization might borrow the format and elements of the business case and the benefits management plan of a successful project. No need to reinvent the wheel, right?
Best.
Eric.