The infamous shoulder region. Not perfect, but the arms can reach a fully raised position without the armpits inflating and shoulders imploding now.
I couldn’t find much in the way of tried and tested techniques for shoulders, so I had to improvise. Weight painting and corrective bones alone weren’t cutting it, so I gave in and slapped on some corrective shape keys driven by the upper arm rotations.
Now the bones, corrective bones, corrective shapes and two body shapes (male and female) were all fighting it out for dominance, but I gradually wrestled it under control by aligning the topologies of the body shapes more closely, constantly massaging the corrective shapes and tweaking the weight balance.
If I were to start over I think I’d ditch the corrective bones, give it an even coat of weight paint and do the heavy lifting with corrective shapes. It’s just easier to shape things with shape keys.
https://twitter.com/cjones3D/status/1174957846812741632?s=20