Kjay:
Remember....the NEC is not a design manual.
On a 'plain vanilla box space'; as an AHJ, I have to plan review based on code compliance of mandatory required items. Hence, a single 120 volt, 20 amp 'sign' circuit is compliant. It would be up to the tenant fit-up plans to indicate exterior signage loads, and if any additional circuits would be required, which would have to be code compliant.
Yes, wording within the NEC can be questionable to say the least.
