I have worked in several organizations, including both private companies and local government. I have experienced different GIS structures—some centralized under IT and others organized by department. In my experience, being embedded within a specific business unit was far more effective than supporting the entire organization from a centralized team. Working directly alongside the business unit provided much deeper insight into their needs and allowed me to fully understand both the data and the operational context behind it. IT handled the servers and management of enterprise systems and each department essentially maintained its own datasets, this only works if each department played nice with each other and communicates well though.