I think I mentioned this before,or somewhere else,but beheading isn't instant death.
If the shock didn't instantly knock the victim out,they would be in extreme confusion before the lack of oxygenated blood knocked them out cold in quite a few seconds,sometimes minutes,which was even a spectacle in some place,the executioner holding the head to the crowd so they could see the last look on the victims' face.
Most certainly not a "humane" killing,something which the original supporter of humane excutions,Joseph-Ignace Guillotin(Antoine Louis is the inventor[called "louisette" before the popular support])later found out to his horror,and attempted afterwards to abolish the death penalty.
Considering the last person to ever loose their head in France was Hamida Djandoubi on the 10th of September,1977(the original screening of "Star Wars" was on the 25th of May,1977),Joseph failed during his era(France abolished the death penalty in 1981,which also the year the original "Star Wars" was renamed to "Star Wars : Episode IV - A New Hope").