Training shoulders is a subject that everyone in the fitness industry has their own take on. Train them with high reps, train them with low reps, beginning of the week, end of the week, there are countless different ways that people will tell you to train them. My opinion is that there are a lot of different approaches that will work but with varying degrees of success. Take it from me I've trained them at all different times of the week with all different types of approaches but let me share with you the approach that has worked out best for me and given me big, full, vascular shoulders.
Train your shoulders with frequency:
Designating one day a week for shoulders as with most body parts will give you some shoulder development but what I have found is that when I incorporate shoulders two or even three times per week I get the most development. Hammering them into the ground and walking out of the gym looking like Quasimoto is one approach but I find that my shoulders respond better to a controlled approach several times per week.
Varying your rep ranges helps a lot:
People fall in love with a certain rep range for training their shoulders. You will see people training them with no sets believe 25 reps and we have all seen the guy using his legs to get the 50 pound dumbbells up for a 3 rep set of lateral raises (don't be this guy). What I have found is that if I stick to keeping presses heavy and my assistance movements light I get the best of both worlds. Stick to 3-5 reps sets of your barbell and dumbbell presses and 8-12 reps on anything like lateral raises and rear delts.
Nix the front raises for additional presses:
I know this one will strike some people the wrong way but trust me when I say that pressing will hit your front delts sufficiently. Most studies show that a lot of the tension from presses is on your front delts. So opt for the exercises that allow you to move the most weight while simultaneously being safer. Don't use your legs to try and lug up weight that is too heavy for you on heavy upright rows or front raises add in some additional heavy presses for increased size in your shoulders.
Here is how I am training my shoulders right now:
I take my heavy pressing approach to my shoulders on Tuesdays and Thursdays and pair them up with one additional exercise typically being dumbbell lateral raises and machine rear delt. Saturdays I will train presses with a bodybuilders approach with high reps while focusing on a quality range of motion. This is the approach that has worked best for me in order to create big, strong, full shoulders.