When I first injured my shoulder I was doing exercises 3x daily 5-6 days a week. That was rehab though and w/ extremely light weights (5lbs or black theraband). I actually saw pretty explosive growth in my shoulders while doing this, but then again I was 19 and had never really lifted shoulders before. I continued doing the same routine 2 days a week as my regular shoulder day...it was a few years later that I actually added military and other shoulder lifts in.
Since I started my HST program (almost 2 months ago) I've neglected my RC workout...after reading this thread I may just add it on to a Sunday cardio session, light weights like sugarplum said just to get some blood flowing.