Modern mass production (iirc 1900s and later) where each person basically hyperspecializes in one job on an assembly line tends to cause repetitive strain injuries as people are doing the same handful of movements quickly thousands of times a shift. A good factory will shift people around to different parts of the assembly line to try and delay injuries as those will cause more efficiency loss than the hit you get from moving someone from one position on the line to another (sometimes it's even just as small as just having them be on the other side of the conveyor doing the same job).