Once you can do a 600-700+ lb partial deadlift I doubt your traps will be lacking...
Not there yet? Then it becomes obvious what you should do...do the exercise with only 1-2 work sets, leaving you ample resources to recover, and ADD WEIGHT TO THAT BAR EVERY SINGLE WEEK. You may be at, say a 200-300 lb level now, but if you TRIPLED your weight you were pulling, your back will be a LOT bigger/thicker.