A couple of things I noticed, but first, that’s not the same character in the same pose as your first post, so I can’t say what was wrong there. With this character, I noticed a few things… First off, if I rotate the upper arm 90 degrees so the palms of the hands are facing forwards, it pinches in the shoulder area again. I think a bit more careful weight painting might cure some of it and again, as I showed with my illustration, just don’t pose it in such extreme poses. If you must pose in extreme poses, then there are other methods for correcting the pinching problems. However, I firmly believe that good topology and careful weight painting can correct 90% of all problems, then if it’s still a problem, look to the other methods to correct the problems.
So after I rotated the upper arm and got the pinching, I rotated the lower arm in an attempt to match the pose in the pic you posted and there were more problems in the elbow area. Try it for yourself, just rotate the lower arm and look at how it deforms… It’s really bad and here’s what is causing the most of the problems:
In this screenshot, the blue dot is where the elbow joint is on your rig, according to the topology, the red dot is where the elbow joint should be. The two yellow lines indicate how I’d have those edge loops flow in that area, sort of spread out on the inside of the arm.
Did you weight paint this yourself, of just use auto weighting? When I rig a character, I create the basic rig & weight paint it by hand, auto-weighting is sloppy at best. Then I pose the character in extreme poses, and correct the weight paint as needed. As I add controllers & constraints to the basic rig & test them out, I’ll stumble across bad deformations again, so it’s back to weight painting again to correct the problems. So basically, the entire time I’m rigging, I’m refining the weight painting. In the end, I end up with a really good weight paint job.
Hope this helps,
Edit: I also noticed but forgot to mention that you’re not using the subsurface modifier on this character, that can help to smooth out problems as well.