40 seconds? When I do cervical dislocation, they're pretty much stiff by 40 seconds. Thrashing is done by about 10, I think. Haven't counted exactly.
I haven't done birds for consumption yet, but I plan to try the pipe cutters or loppers. Seems quick and easy.
I was just going by what the poultry veterinarian said as far as time to death. Maybe he is talking about the death of the brain rather than the death of the body? I notice that even decapitated, the beak will continue to open and close for a few seconds. Like you, I haven't timed it, but I really like these different lopper/cutter tools.