I think cultural integration is a multi-tiered / multi-channel effort that should be thoughtfully considered based on the specific cultural issues, enablers, or barriers that were identified through due diligence. Then the workstream/activities should be carefully planned and executed as a part of the broader integration plan. There may be other cultural factors that are identified in the PMI environment that can be considered for incorporation to the overall plan (i.e. plan, execute, assess, adjust).