Kyle: some of the following may seem counterintuitive, however they are based on empirical evidence. To keep this short I'm not to elaborate on the basis unless you specifically ask.

Here is a quick test to determine your level of understanding in training principles. I'm not being condescending here. I wasted 20 years following bad advice and would have been grateful if someone pointed this out to me long ago.

Do you know that:
1. Training Intensity (weight) and Volume are inversely related? You can't simultaneously train both.
2. Smaller muscle groups recover move quickly and can handle a greater number of sets with shorter rest periods that larger muscle groups.
3. The eccentric phase of a lift is at least as important as the concentric phase.
4. You will adapt to a routine in 6 sessions. So if training a muscle group 2 times per week, then you should change routines at the end of each 3 week period. Any longer and you are training sub-optimal.

My view is that the best approach is to alternate between strength and size every 3 weeks following a periodized program. If you are still interested I can send you a specific routine.

To answer your question directly, I need to know your entire routine including:
Exercise, weight, sets, reps, tempo (time lifting the weight and lowering the weight for each rep) and rest period. Training days per week. Most people overtrain. Are you adding one rep or 2% in weight each training session? If not something is wrong.

This may not apply to you but I haven't trained shoulders directly in a while and they are growing.

Check out Charles Poliquin's "Poliquin Principles".

Dossier: If you have been doing bench presses at every pec training session for years, then it's possible you have a structural imbalance between the internal and external rotators of the humerus. It will be exacerbated if you work at a desk or computer all day. Unfortunately this will also lead to shoulder injury (a very complaint among those that have been training for years).

There are several exercises that will work the external rotators. When your arm is abducted and high with respect to your waist the infraspinatus is more active. Arm in front and low with respect to waist, then the teres minor is more active. There are a bunch of exercises that work these muscles directly. I need to run out to an appt. If you want specific descriptions I am happy to provide them, let me know.