Has anyone formalized a customer executive sponsorship program within their CS org?

Curious as to the processes. To be clear, this is a process where senior ( V or C level) executive team within your organization, develop an active role or relationship with the executive manager (usually C level) of the customer. It's worth mentioning that this is specifically for top segment/enterprise customers, since the tactics for non-enterprise will be different. Also how, if at all, does the CSM come into play here?  TIA awesome community!