Building the wall sections in a shop is great. Right now I'm getting my BS in Construction Mngt. Each year we build a house for program. The walls are built in our shop, then taken to the site when we are ready to frame. With a group of about 10-12 guys, we did the floor joist in one 4 hour period. The next class period we framed up the first floor, next perior second floor-joists, next period second story walls framed. So in about 16 hours, 4 class periods of 4 hours we had completely framed a two story 2800sqft. house. That included interior walls as well. There are more and more medium to large scale residential contractors doing the shop built walls becuase it cuts down on time as well as errors/waste. The amount of waste produced onsite versus shop built is incredible, and who do you think picks up the bill for that...the buyer! Plus there's always something to do when the weather doesn't permit you to work on site. If I ever start building houses, that will be the direction I go.