Surface mount of new service. cable protection

I am mounting a new service panel. It is in an ICF house and is surface mounted on plywood. What are the rules for running romex to the panel and using "SE" cable exposed. Someone told me that as long as the cables are over 7' high no protection is required. What is the rule ? Can I run romex tacked to the plywood so long as it is fastened or must it be covered?

Thanks in advance