I know there has been a lot written on these pages on the question of whether it's better to bleed or chop. I've read the opinions, and I can't bring myself to bleed. It seems too drawn-out to me. I prefer the sudden and final act of the hatchet.
Here's how I prevent any misfires: I have a heavy timber (4" x 8" about two feet long) with two big galvanized framing nails driven partly in at one end. They are driven in at an angle, with their points pretty close together, and their heads spread outward, in a V. I grab a rooster by his feet, hold him over the block of wood, set him down head-first into the V, and when I pull back on his feet, his head is held by the V, immobilized, and his neck is stretched out. Then, quickly, with my other hand (the one that isn't pulling lightly on his feet to keep a little tension on his head against the nails) I swing a sharpened hatchet. Because it's not a moving target, and because he's tight up against the chopping block, it's always a clean chop. Then I hang him by the feet on a clip made out of bent wire, over a bucket, and let him bleed out. From grabbing a surprised rooster by the feet to hanging a headless flapping rooster over a bucket, the whole thing takes seconds, and there's no chance for anything to go wrong.
That's just my 2 cents on how I assure myself of a clean, humane, quick and sudden chop.
(edited to fix spelling)