Which of the following is NOT a step in the governance system design flow?

The correct choice reflects that reviewing past governance models is not explicitly outlined as a step in the governance system design flow. The focus in governance system design is primarily on understanding the current enterprise context, strategies, and determining the specific scope necessary for effective governance.

Understanding the enterprise context and strategy is crucial as it sets the foundation for the governance framework by aligning it with the goals and objectives of the organization. Likewise, determining the initial scope helps to delineate the boundaries of governance to ensure that it addresses the relevant areas effectively. Concluding the governance system design brings all the elements together, finalizing the framework to be implemented.

While reviewing past governance models may be valuable for gaining insights or lessons learned, it is not a formal step in the structured design process of a governance system as outlined by governance frameworks like COBIT. Thus, identifying it as not part of the design flow aligns with a focused approach to developing a governance system tailored to current organizational needs and future aspirations.