The Iron Maiden was principally used in Germany. Look at the spikes on the inside of the door. Both doors had similar spikes. When the accused was inside, the doors were closed slowly. The object was not to use the Iron Maid to quickly kill someone. The object was to inflict pain and punishment.
Although an accurate history of the Iron Maiden of Nuremberg is not exactly clear, there is evidence (perhaps unreliable) it was used as early as August 14, 1515. On that day, a German who had forged coins was tortured with the device. As the doors were slowly shut, spikes penetrated the forger's body just enough to cause excruciating anguish but not enough to kill him. Crying in vain, the forger lived two days.
Like the Iron Maiden, hanging was intended to draw out the death process. Not hanging where death came quickly (the "English drop"). Hanging where death came slowly and torturously.