Yeah I’ve often done the banded distraction capsule mobilisation, I’ve done it in both external and internal rotation. I went through a period where I did it for a few months every day 2 min each side and as you noted I did the couch with the band before I did this mobilisation so as not to wreak what I had fixed…
What I found was:
_It helped the bottom position of the squat
_It did slightly increase the range of internal rotation
_It increased my range in the pike