Ok so running PVC conduit is out of the question for vertical runs through my 1923 ballon framed house.

But now the issue is when I go to "re-organize" my electric (pretty much everything is on two circuits) can I place 7 #12/2 runs into the 16" on center, wall cavity between studs with space in between the individual wires?

This will allow me the flexibility to set up j boxes in the attic and simply drop lines down from the unfinished attic into the seperate rooms which will now be on individual circuits.