Reality Based Kyusho
Yeah, it would probably take that long to die of a splenic fracture, probably take a couple of days to die of a carotid dissection from black tiger, probably only would take one day to die of a subclavian artery laceration from seiuchin black tiger. I wonder how many people they would have had to kill using these methods to see that pattern.
The Myth is Actually a REALITY
But not even some Kyusho practitioners understand this, as they still adhere to the Pressure Points (Acupuncture) as the working model. Some of them actually believe they can stop or reverse the Chi flow to attain this, but that is the fringe of those groups. However it is very real when working with real anatomical structures, especially the blood and organ system.
We need to remember the time when the "Delayed Death Touch" was documented, it was a time before hospitals and modern medical practices. So a rupture to the spleen, kidney or liver would take from minutes to hours to days before it became fatal. We should also remember that the warrior of these times virtually lived and died on the battlefield, where hand t hand with bladed weapons was the reality. They felt the weapon penetrate or slice through the bodies, they witnessed fellow warriors and enemies alike perish from these wounds.
Possible from the Bubishi Targets
The Bubishi is complex and confusing for most until you understand the keys to open the ideology and documented realities of observed combat. This is not myth even though many ignore this ancient military workbook as such... to their loss. One of the more confusing aspects is the targets called Shichen in Article 21, titled; "Delayed Death Touch Twelve Hour Diagram".
As the modern translations of this ancient manual have emerged, it is difficult to discover the real possibilities with the inaccurate use of the acupuncture points as the model. However when cross referenced with other similar documents, scrolls, Bubishi's and compiled target systems of ancient arts, linked with the keys to achieve success with tools and trajectories, the truth emerges.
The claim of "Death in One Day" using the "Rat Shichen" seems at first to be only legend, but when linked with real anatomy and physiological function, trauma at these locations would indicate the reality that modern medical science still observes.