Here on the sc coast, and we are basically at sea level, nema 3 rated devices just dont cut it with the salt air.I have changed many meter guts due to corrosion from salt. Imagine what the service calls would be like if the load centers's were outside.They are however starting to require main discos. on the outside for fire reasons, that SER cable aint cheap..
As for the 6 foot rule; my understanding is that along any interior wall there should be no more than a 6 foot difference at any point along the floor between receptales.Most lamps or appliances have a 6 foot whip, so if you are 12 feet between recepts. you can plug them in without the use of an extension cord, anywhere between the plugs.
