I thought I'd post a little problem I've experienced in the gym to help out some noobs or anyone with a similar problem.
Back when I was starting out I had some difficulties developing my delts. So, I figured there could be 2 reasons why this is so, first, genetics, and second, overtraining.
I ruled out the first because I do not beleive in excuses for anything so I thought it must be the second, overtraining. Well, I revised my training and dramatically reduced the volume for "shoulder day" and experienced little change. I once again found myself at the drawing board. I then reduced my volume even further with no results again.
I then thought well you hit shoulders with chest and back so if you throw in a shoulder day on top of all that you're relaly hitting shoulders 3x/week. So, I completely erased shoulder day and only added lateral raises to my chest day. The results were astonishing! My shoulders capped right over and the width increase dramatically within only about 2 weeks.
Point of the story, it's very easy to over train your delts and any other muscle for that matter. If you are experiencing any type of lagging bodypart back off, or take a break from the gym if you experience major symptoms of overtraining (insomnia, exhaustion, lack of motivation, muscle/strength loss, etc) as overtraining is one of the major hypertrophy suppressants.
Like I said up top, this post probably isn't for the experienced, but for the guys starting out as I find a lot of newbies try to work through this slump with more training, volume, sets, etc.
Less is sometimes more in the game.