I'd be glad to throw my opinion in here if you'd like. First off I'm impressed by the fact you train your post delt (90% of meat heads train only the things they see in the mirror) But as a guy that can proudly say that shoulders are my favorite body part to train, here are a few things I'd like to share.
It won't matter what exercises your doing, if you're trying to gain MASS. Then you need two things, heavy reps and heavier caloric intake. Eat like a monster and train HEAVY.
2) Rep Range:
I like the 8 to 10. But I'll tell you what, if you haven't gained mass it's because you're not going heavy enough. Increase the intensity and decrease the volume. Go for sets of 5-8 and make damn sure that by that 5th rep you're burn'n. If you COULD hit 9 Then that weight's too light brotha.
3)# of Sets
There are three factors that go into you wondering if you're training enough sets on shoulder day. a) Am I getting bigger? b) Am I sore the next day? c) Did I nail every muscle fiber in the shoulder complex on the head?
From what I can see from your program it looks like there's no's across all three. SO here's the fix. MORE, yes i said MORE sets. Believe it or not 5 sets of 5 would be optimum. Here's the reason. Say you're doing military press for 3x10 w/45 lb. DB's. Thats thirty reps with 45 lbs which means you moved 1450 lbs worth of total weight. Now go 5x5 w/65 lb. DB's. Thats 25 reps with 65 lbs. which means 1625 lbs were moved. yep, that's nearly 200 lbs more weight that your muscles had to endure which = Growth.
Now I really like the exercises you've chosen here. Only a couple things. One, Overhead DB press and Upright row are def not interchangeable. If you want a pure mass building exercise for those traps(which I greatly recommend you train on shoulder day) old school shrugs my friend. Heavy and stick that at it's highest point for a full second each rep. Remember this IS shoulder day. So don't worry about what may or may not of been worked on other days.
Hit everything. Anterior/Med/Post head of the delt. Upper and middle traps, Rotator cuff. Now granted we're at different places in our training experience perhaps, but let me put my shoulder workout on here and if you have anymore questions I'd be happy to help out anyway i can. Or if you dont like what i said tell me to eat it. haha either way here it is.
Warm-up with rotator cuff and scap work
Seated DB over head press
Standing BB Push Press
DB Lateral Raise
Superset: BB Front Raise with DB Rear Delt
BB Power Shrugs
Towel Grip Up-right Rows
Manual neck work with partner.