I'm not in this space, on either the athlete or the biomedical side - but it sounds like a "more is better" running mindset and mythos is colliding with the biological realities of human bodies which either (1) Were not carefully designed for this kind of duty cycle, or (2) Have accumulated quite a few deleterious mutations in the generations since that design, resulting in frequent operational failures at well below the hoped-for spec.

Might anyone know if indigenous groups such as the https://en.wikipedia.org/wiki/Rar%C3%A1muri - where extreme distance running seems part of their traditional culture - have been studied in this regard?