My shoulders are one of my better parts, so I usually stick to a couple of pressing movements and one head specific movement. It does change though, at the moment I do dumbell presses x 3, upright rows x 3 and standing laterals x 3.
The reason for only 6 sets for bi's/tri's is that I'm a hardgainer and my arms seem to do OK from this kind of volume. I do occasionally do a specific arms day with bi/tri supersets for 3 sets of 3 exercises, but I generally don't give them too much volume. I know if I do too many sets for my bi's especially, they weaken very quickly.
