well since this old threads been bumped already
i train traps once a week directly on my back day, always found ive needed to train them to get good growth
give it 30-40 more pounds n ill be shruging 500s easy
plus IMO helps heaps getting ur deadlifts up and improves ur handgrip strength big time
big shrugs will give you nice man hands
calluses all the way baby
shrugging 500+ is already easy though.