My buddy Mike had a crew out in Dayton last spring and watched them frame a whole basement in two days. They were just slapping studs up and checking plumb with their eyeballs, no string line anywhere. By the time they got to the back wall, the door header was off by damn near two inches from the front one. Took them three hours to rip it all out and redo it. Honestly, @karenhenderson, you're spot on about the chalk lines, Mike said the floor marks were still faintly visible from the original layout but the kids never used em once.