I've done it once, just to show some of my son's friends why I don't do it like that - it makes a mess. Blood everywhere. More effective: I hang them upside down, they calm down really quickly. I stroke their neck softly to get them to relax, then using a razor sharp blade, I carefully make slits on their neck & allow them to bleed out. They never even flinch when I cut through those jugulars or carotids, or whatever they are. The blood just runs out into a bucket below them. (I don't want my yard to look like a Friday 13th setting) It would sort of be like going in for a blood donation, but they kept taking blood out of you until you passed out and eventually bled to death. You can even watch their eyes eventually shut as if they're falling asleep. It's probably about as painless as possible for the chicken, and it's more effective at getting the blood out of the meat.
Cutting their heads off and having them run around is just morbid. And messy.