Most KOTOR2 levels were done by one artist, and took 2-3 weeks to model, texture, and light.
After all the levels were finished, many were given an extra week for polish; often by a different level artist.
One of my favorite levels that I built, the Peragus Station Hanger, took me 3 weeks (it was the first area I built for the game). It was masterfully polished by Tim Cox.
Another favorite, the Telos Station Entertainment mod, was done in 2 weeks.
Ed Lacabane helped with this area, by initially building the cop station, merchant shop, and cantina. I spent an additional week polishing the entire area.