The rule requires that no point on the floor be more than 6' from a receptacle.
If you place the outlets every 12' than no point along the floor line will be further than 6' from at least one receptacle.
Quote
210.52(A)(1) Spacing. Receptacles shall be installed so that no point measured horizontally along the floor line in any wall space is more than 1.8 m (6 ft) from a receptacle outlet.
Bob Badger Construction & Maintenance Electrician Massachusetts
