Ive always trained with the idea that traps,abs,calves,forearms and rear delts can be trained just about everyday. Im not sure how much deadlifting your doing, but Id probabally only shrug once a week on shoulder or back day if I was doing deadlifts. Also, traps is one of my best body parts and the first thing to grow on me, so I dont even train them at this point. I deadlift alot and that seems to have been sufficient. If youre recovering well, Id say stay with it. If the soreness is interfering with your workouts then Id say cut out one of the shrugging days. Hope that helps!!