You are correct regarding how this would be built in reality, however, I wanted the slab at the outside edge of the building for modeling/2D reasons, including early dimensioning and "magic wanding" purposes. I figured the building material cleanup in section would take care of any shortcuts regarding the slab. The top and bottom layers of the slab were concrete sandwiching the rigid insulation. As it turned out, the complex profile as a wall didn't cut the insulation at all, even though it was set as a lower priority material. Interestingly, when I used the same profile as a BEAM, everything was cut properly. (Also, the beam had the nice feature of providing a hidden line for the footing below. I probably should have used that in the first place. Walls don't create the automatic hidden lines under slabs that beams do.)
The only reason my brain went first to the complex wall rather than the complex beam was the ability to easily magic wand the footing around the slab accurately, since beams use their axis which required more adjustment. Going then to section, I was perplexed that it wasn't cleaning up the way I expected, and called tech support to figure out why.
I think what bothers me most about this experience is the apparent automatic assumption that users probably just don't know how to use the program correctly, and now need to pay extra to get the inside secret that the user inadvertently overlooked. Given how complex GS has now made this program (e.g the stair/railing tool), it feels like GS is now trying to profit from the complexity that they created themselves.
Richard Morrison, Architect-Interior Designer
AC25 (since AC6.0), Win10