Train your weakest body parts twice per week and you might just make them that tiny bit bigger!
My delts have always been a lagging body part and after consistently hitting them 2X per week they are starting to develop, even though I'm on a cutting diet... I try to hit them from every single angle possible and pause at the top of most isolation movements, such as side raises, for a good 2-3 seconds to really engage my delts and feel that deep burn.
I believe delts in particular respond to really controlled movements, with 0 swinging and great contractions.
Let's say that your delts are a lagging body part and to be more specific your front delts, which are actually my weakest part...
"If you're looking to improve your shoulders I would suggest training them twice a week, once every 3-4 days"
Your first workout might be a heavier workout in the rep ranges of 8-10 and your second day might be a lighter, higher rep day, focusing on a deeper burn and better pump in the rep ranges of 10-12.
A great shoulder workout with AN emphasis on your front delts