A kill plant only cares about speed. A single large facility like Maple Lodge Farms kills half a million chickens daily. The greatest thing you can do to reduce suffering is to eat less or no chicken.
Background image from a Mercy For Animals video
I got to thinking about the highly efficient and dispassionate process used in both cases, that the perpetrators felt no guilt ... that my fellow Jews were transported in cattle cars.
Birds are grabbed from a transport crate every 3.5 seconds. Some birds get hung by one leg, which leads to further injury down the line.
Birds that lift their heads don't get stunned. If they are still moving, the blade can slice their body instead. Birds can miss the blade and get drowned in the scald tank.
At smaller facilities, including kosher and halal facilities, necks of fully conscious birds are cut by hand. Someone has the job of standing covered in blood, every day slicing necks. Killing using inert gases is more humane and less gruesome.