i agree with high volume high weight. i work with a very heavy 5RM power shrug and start pyramiding down when i can only get 3-4 reps with the weight (i usually get to this point at about 20 reps), and do about 40 reps total.
around that time i hit 40 reps, weights and velocity start to decrease more and more so i switch to a different rep scheme, 30 reps at my 10RM for dumbbell shrugs. then, 20 reps with a behind the back smith machine shrug using the same total weight as the previous exercise.
i finish with a super long extended set of shrugs with the shoulder-padded calf raise machine starting at the same 10RM as before and just keep going up the stack maybe 8-10 times, emphasizing a 2-3 second hold at the top, a slow negative, and a stretch at the bottom. burns like a mother.
my grip was a problem so i ditched the straps, lo and behold, my grip strength caught up. definitely use chalk for the BB and DB though. also, IMO it's ok to apply just enough body english to shrug explosively with the BB/DB as long as you can perform a tight squeeze and hold at the top and start from all the way at the bottom.