Great Post and Great thread. As I have stated in another thread, I am a fan of some of Charles Glass' practice/theory. His shoulder video/routine
is almost identical to what you do, except he uses a Smith Machine Seated Press instead of your Behind the Neck Press. When I was doing a 4 day split, that was my basic routine. What I experienced was a decrease in shoulder pain and an increase in overall strength. I just noticed that Glass puts rear delt work on back day also. What does all this mean? Absolutely nothing, but I feel better having shared it with you.
Have a great day.