Twenty years ago I was creating skeletons with extra Clavicle bones between the base spine root joint and the shoulder to account for more realistic character deformation of the shoulders. Once the shoulder rotates up, the clavicle should be adjustable independently to get a natural deformation as the clavicle plays a major role in raising your arms. As it stands, the shoulder is entirely independent of the clavicle and raising the arm above the head leaves you with totally unrealistic results. With all of the progress that's been made with shaders, someone dropped the ball on joints. Also, I used joints at the hips to clean up the collapse of the pelvis/hip when a leg kicks out to the side.

I've worked with character modeling professionally for over 15 years and I can tell you that I know what works. At least allow for adding additional joints without a pipeline that involves some other software.