If you look back at this post, you'll see I was having issues with a shirt-arm-back pulling thing. I think I know how to fix it on subsequent patterns. Here is what I did to this New Look pattern to test it out. I took out 1/2" between the shoulder and bust in the front and the back. The shirt is pretty much unwearable but I was going to pitch it anyway.
The blue lines are where I put the stitches and took out that 1/2".
Look, I can lift my arms! It is amazing what 1/2" does for you.
This weird shoulder pucker is why the shirt is unwearable.
Inside the shirt so you can see where I took the 1/2" from.