Alan, our code has, for a very long time, mandated that residences have the receptacles spaced so that no point along the floor, where the floor meets the wall, is more than six ft. from a receptacle.
Receptacles on the floor, within 18" of the wall, and wall receptacles 5'6" or lower are considered in meeting this requirement.
The effect of this rule all too often is poor receptacle placement. The electrician will enter the room, measure off six ft. from the door, then start placing receptacles on a 12-ft spacing. All too often, (since most rooms are 12x12. or smaller), is that the receptacles wind up in the middle of, and behind, furniture.
