I am in the process of helping a customer with Marketing Cloud setup and they only have one CRM instance. However I am recommending for Multi-Org enabled though they have one CRM instance. My rational is not to do any development(automation, journeys etc) at Parent business unit except Administration(create users, roles etc) and all the development will be done at child business unit which will be connected to the CRM instance.
Do you think it is a best approach in the long term? Would appreciate any input.