How many bones we need for low polygon models?

Japanese deformation characters don't need many bones, if the camera is far enough from models. I am trying to check how many minimum bones are.

When I was an animator and was drawing "DETECTIVE CONAN (Case Closed)", I felt that Japanese deformation characters need 12 bones to animate basic actions --- One spline, one neck bone, three leg bones and two arm bones.

This is a half of common 24 bones, and omits major 6-7 bones --- hands, shoulders, divided spines and a waist bone. I added some of them to the minimum bones.

eg) XSI default character Rig;