I'll have to ask Jay again, but I'm thinking he told me it took an average of 3 days for the work to be completed. I've been over there several time when trucks were up on the lift being worked on, and they were intact except for the bed having been removed and set aside.
Speaking of frames being replaced, my Aunt Julie had a new '72 Chevelle Malibu wagon. After having it only about 6 weeks, she got rear-ended at a stop light. The frame was bent, along with the tailgate, rear quarter panels, roof buckled, bumper pushed in, and rear load floor buckled. She was able to drive it home (only a few blocks), and then took it to the body shop. After a couple weeks, she went to see about it. They had to disassemble it entirely, and she saw what hadn't been scrapped sitting in pieces - doors, front fenders, interior, etc. It was at the shop about 6 weeks, but when it came back it was just like nothing ever happened. She said the repairs cost within a few hundred dollars of what it cost new. That wouldn't likely be done today, but labor wasn't nearly so expensive then.