A interesting quote below about the cutting test process used by Yamada that would occur prior to his cut test from the book "Tameshigiri - The History and Development of Japanese Sword Testing" By Markus Sesko  page 41.  Available for purchase - click here.

Quote from Joly & Hogitaro´s 1913 publication The Sword and Samé wherein we find a description of the tameshigiri procedure: "Corpses which are used for tests are supplied by the machi-bugyō on the demand of koshimono-bugyō [weapon´s magistrate of the bakufu]. On the day of the test two dotan are built, the examiner's seat is one single thin mat, the ground between the examiner's seat and tameshiba is sanded, and on it stand Yamada Asa´emon and his followers. At a fixed time, when an execution is completed, the officials return to their offices, while corpses are lying on the tameshiba with their heads. Honami the sword expert and his pupils come then, and also the consultant metsuke. The koshimono-bugyō comes later and is received by the metsuke at the entrance to the searching office. When everything is ready an announcement to that effect is made by a gaoler. All people assemble at the examiner's seat with the koshimono-bugyō and his assistant, together with swords in boxe). The metsuke is seated on the side of the tameshiba, together with the prison watchman … Yamada Asa´emon and his assistants dressed in black kimono with a band of check or stripe at the edge of the sleeves and waist ... The entrance is guarded … and the public kept out. The main gate is also guarded ... The corpse is then adjusted on the dotan by two hinin directed by Yamada Asa´emon, one man hands the blade to Asa´emon, who lifts it to his forehead and fits it into the kiri-tsuka [more on that later], then he takes off the upper kataginu part of his kamishimo and his kimono, faces the dotan and places the back of the sword on the corpse, holding the tsuka in the right hand, with the left he touches the ground and salutes the examiner. Then he stands up, grasps the sword with both hands thrown back over his head (the blade almost vertically downwards), and when all his muscles are taut he cuts the corpse with an exclamation (yah!). Hinin take off the corpse, koshimono-bugyō and other officials approach and examine the dotan, then return to their seats. Subsequently, Asa´emon reports in writing about the condition of the blade."