While global development seems to be moving in the right directions in some areas, like decreasing global poverty and securing access to basic education for all, the mismanagement of natural resources and human affected climate change should be clear indicators for the unsustainable development of our global society. Change is needed. Without any global governance mandated with the management of the global sustainable development others need to step up to the challenge and take responsibility for the current and future survival and equality of our society. Organizational management systems have been suggested to be described through its purpose, principles, practices and tools. As a tool and practice for systematic improvements in quality and sustainability a process-based system model has been developed over the last 20 years. Originally aimed for visualizing the relations between key performance indicators for organizational sustainability, it has evolved towards a generic system model template with several use cases. In this paper the development of the process-based system model is reviewed and revisited for the purpose of identifying further areas of development and highlighting any ambiguities and weaknesses in the model. The key findings are the ambiguity around input, drivers and their relation to external system resources. Future research is suggested to test the usability of the model with its intended audience, used as a sense-making tool, and explore the relation to previously defined system levels with relation to the process view in focus.