Quoting Arnold "I'd like to talk about oblique training. While some will argue against this, I believe that obliques should never be trained with additional weight. My reasoning? Adding weight increases the size of the oblique muscles, which leads to a thicker midsection. That's the last thing for which a bodybuilder should strive. Train your obliques using only your bodyweight."
I have done the weight training and have developed some beastly obliques, I can't seem to find middle ground. What is everyones take on oblique training, I'd rather honestly have a leaner looking midsection and I on the other hand have developed some obliques through training that stand out and take away from lats and shoulders if that makes sense.