Personally I prefer methods where the animal is knocked out and then decapitated. Even assuming a 13 second space of "awareness" [based on average findings] following decapitation, knocking out the animal will make it irrelevant. Or the decapitation could be done over liquid nitrogen freezing the head instantly. However human beings are more concerned with appearances than reducing suffering to the animal.
The knocking out isn't always effective, nor is the electric shock before having the throat cut method.
Does it hurt to have your head frozen in liquid nitrogen? Even for a second?
How do you know?