(C) Where one or more lighting outlets are installed for interior stairways, there shall be a wall switch at each level, and landing level that includes an entry way, to control the lighting outlets where the stairway between the floor levels has six risers or more.
Would this require a 3-way switching device in both an unfinished attic and basement?
I don't think it would because is clearly says "landing level that includes an entry way."
I agree the 3 way on the steps is really a design issue but I would want the EC to try to explain this design choice, with a straight face. "OK so the plan is, you turn on the bottom light, go upstairs, turn on the top light, then go down and turn off the bottom light and go back up, turning off that light as you go on down the hall".
If the EC can say "yes that was my plan" without one of us laughing I guess I have to accept it.
I remember living in a 2 floor apartment once that didn't have 3 ways... the stairs were right as you walk in the door to the right, so the entryway light covered the bottom floor.. but then once you got upstairs, you had to get to the opposite wall of the hallway to turn on the upstairs light...
I always did think it was annoying having to walk down or up in the dark, or just leave it on