An operating model has four parts: the domains and their owners, the roles and how much time each carries, the forums and what each one decides, and the routes — how a definition gets changed, how an issue gets escalated, how an exception gets approved. It also declares a shape: centralized, federated, or a hub with domain teams. Federated is the most common answer and the least often specified, which is why it so often means nobody.
In practice. Fit the model to the organization you actually have. A company that runs everything through functional heads will not sustain a domain-based model, no matter how correct the domain map is. Governance that fights the existing decision structure loses.
Where it goes wrong. The model is designed for the end state and launched all at once — every domain, every role, every forum, on the same date. Capacity does not exist, the forums do not fill, and eighteen months later the model is a document that describes a thing that never happened. Two domains done properly beats twelve announced.