If all you do are Shrugs, yet you still are not experiencing signifigant growth, you fall into the class(like me) of lifter that needs to do compound movements to build traps brother. You need DEADS & POWER CLEANS added to your isolation movements(shrugs). Try(if you don't already) switching your workout to doing Back/Traps on the same day. I hit 10 sets for Back. How many sets I do in DEADLIFTS during my back routine, I also count towards sets for TRAPS. For this reason, I have been doing Deads as the last exercise during my back routine. 2 sets of 10 reps at the end, which counts towards 2 sets against traps as well. Follow up with another compound movement---Power Cleans-2 sets(1 warmup, 1 heavy). Then go to your isolation exercises. 2 sets of shrugs--do shrugs LIGHT with FULL RANGE of motion bro. Then 2 sets of close-grip upright rows. When you do upright-rows for Traps, you should pull the bar up to eyeball-level, as opposed to simply having the upper arm being parralel to the floor, as they are often performed when the front delt is being targeted. Don't allow your arms to extend the whole way either. For continuous tension, I usually do these with cables. That's 8 sets. Maybe finish up with some dbells at the end. I like to find 4 dbells that I will use, and then run the rack with them. Usually that's 60, 80, 100, 120. No rest.
Deadlifts are the absolute pinnacle of Trapezius building exercises bro. If you do not do Deads, then do them. Do them with standard stance. Use proper form. I guarantee that the next dat you will feel it in your traps, as well as all up the center of your back(spinal erectors). If Deads can't build your traps, then you might be SOL.