One crank at a time is a little slow. Current production rate per shift at GM Spring Hill and Nissan Decherd is hundreds per shift. Nissan forges their own, then finish machines, GM starts with an supplied forging and machines it. Machining cells are impressive to say the least, using turning, turn/milling and turn/broaching to rough and finish journals. Hyundai Montgomery does the same as GM.
I did get to see Mercedes V6 and V8 engine production in Stuttgart years ago; amid all the automation there was a guy by himself using crocus cloth/film tape to touch up journals by hand. Couldn't believe it when I saw it -
Regards,
Steve