We do not stretch in isolation for its own sake. We do not stretch in isolation (since isolation is the most virulent myth) to induce permanent deformation of the tissue to increase flexibility. To begin increasing the plasticity of the body, we stretch locally until the shortrange stiffness is removed. This is a very short and insignificant aspect of preparation. Then we move to engage the organism through a complete range of motion.
There are simple biomechanics involving one joint matrix (such as large arm circles through the 135-degree range of motion), and there are complex ranges of motion comprising multijoint matrixes, which must be modeled and then experienced kinesthetically. All of this information leads to the conclusion that the primary characteristic of maximal flexibility is in the regulation of the stretch reflex through sensitivity to muscular tension and the cultivation of plasticity and viscoelasticity of tissues through yoga.