usually people do not bleed out from transverse cuts at the wrist. If the cuts are angled, there is a real probability of bleed out. Clotting is sufficient to impede the flow of blood through smaller low pressure arteries distant from the heart.
By contrast, the large artery in the upper arm is quite large, and with a single cut there the victim will usually bleed out in less than 5 minutes.
(((:::shudder:::)))