I have had the same question for a while now. My right arm has always been about 1/4 to 1/2 inch bigger and I always wondered how to correct it. I mean if you're training all parts the same then I don't see how. For me it's even more a question of arms vs. the rest of my body. I have always felt like my arms should be another 2 inches to be in proprtion with the rest of me, but I certainly don't want to stop training everything but arms until they catch up. I am currently at 230lbs, 6', 12%, but arms are stuck around 18" and 17 3/4" for the longest time. I was considering changing to one of the posted routines like 5x5's or maybe ever that hst program but everything else is growing fine so I hate to lose ground.