again in real world conditions...you would NOT run that many NMs through a joist. You would drill more holes just to make it easier. I would NEVER have to lube an NM cable to get it through a hole...grab a drill and drill the joists.
Yes a joist is considered a conduit...just remember the next sparky after you, leave him/her a nice place to work in.
This means:
an open/not filled conduit, an easy way to run wire, a CLEAN job, a nice cut in, ACCURATE information...etc
