According to Ripleys believe it or not. In 1939 Erine Hausen set the world record in chicken plucking at 3.5 sec. I would guess without losing his lunch.

I grew up plucking by hand and still do. My great grandma and grandma commercially raised fryers and eggs. We kids were unpaid labor, we butchered about three months of the summer. They only raised white leghorns and bought straight run chicks, cockerels were butchered and pullets were used to replace old hens. When hens were used up they were butchered and sold as stewing hens. My wife and I raise about 50 a year now. I do the plucking she butchers it takes two easy days to finish.
An interesting memory is when I was very young they were sold with the head attached. I don't remember how they were killed but it seems it was pretty gruesome.

my great grandma was a neck ringer ,
not sure I get the gruesome part , it's just food

my Great grandpa also sold feed , 2 free chicks with every sack of feed , if that sounds to good to be true it was , he had sexed them all and you got to cockerel chicks with your feed , white leg horns , you couldn't feed them enough to get to frying size , they were long fed stew birds at best but they were free. and you get what you pay for some times.