The intermediate stage of Six Viscera Realm is characterized by the continual amplification of one's Qi and Blood's power, allowing it to extend beyond one's organs to permeate every tendon and bone throughout the limbs.
The advanced stage of the Six Viscera Realm requires the strengthening of every organ to its maximum potential, until there is no room for further enhancement.
As for the degree to which the power of Qi and Blood strengthens every tendon and bone, there are no rigid requirements.
That's up to the martial artist to decide.
A martial artist's training is constrained by many factors, whether it's their inherent talent or the availability of Silver and martial arts resources.
If a martial artist of the Six Viscera Realm has high expectations for themselves and hopes for future progress in their martial arts cultivation,
They can use various means to enhance the power of Qi and Blood within them and strengthen their martial foundation.