My company creates our own "managed" SAT training that goes out Monthly to all customers. Some customers prefer to have their own cadence or control over the content that goes out. Every quarter when I'm creating the new campaign, I have to manually check and recheck every assigned customer to make sure a customer with their own custom cadence doesn't get assigned and blasted with emails. And over the last several quarters, a customer is getting added who shouldn't and it causes confusion and makes our company look inept.

You can create customer tags. You should be able to create assignments for sub-tenants where IF Company Tag = Standard Cadence THEN assign.