@deck - Thank you so much!
The University of Phoenix stadium took about 5 days to build out in CAD. This was originally for the Katy Perry Super Bowl Halftime show. I re-rendered it recently since I was leading a class in venue buildout (and I originally did it all in Physical). I get 2D AutoCAD or REVIT files to work from and I build it out in Vectorworks. The model stays there for my CAD work on the production design and I push it to Cinema for renderings. The overall scope of the project was about 5 months - so since we lived with the model for so long, it's worthwhile to build it right from the get go.
Some of the stadiums are really symmetrical and you can build out a quart of it and then mirror, but this one was unique in each quadrant.