Decapitation, unconsciousness and death

[spicyfriedtofu]

So I was wondering in another thread about decapitation in relation to hanging. In capital punishment, this is of course considered a mistake and the lenght of drop is calculated to break the neck, yet still keep the head attached. This is sufficient for a quick and effective death. If the drop is too long however, the head comes off. What I am wondering though: does this affect the time it takes to lose unconsciousness?