The success of an IT governance implementation plan is critically dependent on its adoption and integration within the enterprise. Organizational culture, which encompasses the shared values, beliefs, and behaviors, is the most significant factor influencing how change is accepted and managed. A plan designed without considering the existing culture is likely to encounter resistance, leading to low adoption rates and ultimate failure. Therefore, tailoring the implementation approach, communication strategy, and change management activities to the specific cultural context is the most important consideration for ensuring the plan is realistic, effective, and sustainable.

A. Principles and policies are the core components of the governance framework; they are what is being implemented, not the primary consideration for the implementation plan's design.
B. Roles and responsibilities are essential elements defined within the governance framework, but their successful assignment and execution depend heavily on the organization's cultural acceptance.
C. Risk tolerance levels are a key strategic input that helps define the content and objectives of the governance framework, rather than the methodology for its implementation.

1. ISACA, CGEIT Review Manual, 8th Edition, 2020. In Domain 4: Governance Implementation, Task G4.1, the manual emphasizes that the implementation plan must be tailored to the specific context of the enterprise, which explicitly includes its culture, to ensure success.

2. ISACA, COBIT 2019 Implementation Guide, 2018. Chapter 4, "The Implementation Life Cycle," details the phases of implementation. Phase 3, "Create a desire to change," and Phase 5, "Embed new approaches," are entirely focused on managing organizational and behavioral change, underscoring that cultural readiness is a prerequisite for successful implementation.

3. De Haes, S., & Van Grembergen, W. (2009). An exploratory study into IT governance implementations and its impact on business/IT alignment. Information Systems Management, 26(2), 123-137. The study highlights that implementing IT governance is fundamentally an organizational change initiative, and factors like communication and resistance to change (cultural elements) are critical success factors. (https://doi.org/10.1080/10580530902794786)