Heres my advice, it works extremely well if you really train hard... After you've done your primary exercise (whatever you work traps with).. Go to the power rack and do 3 working sets 8-10 reps of rear barbell shrugs from behind, move the barbell all the way to the rack so it looks like a smith machine, bent forward and grab the bar from behind, all the way up all the way down squeeze.... next move to the dumbell shrugs, 4 sets of 12-15 reps, make sure to bring the dumbells all the way down to get a stretch on your traps and come up squeeze hard..
Forgot to mention that twice a weeks works best..