Personally, I've always felt that given the extreme force applied when doing clamp work that we shouldn't make a habit of doing clamped exercises every day. My theory behind this is that in due time, the tunica will begin to strengthen and adapt to the amount of pressure applied to it by clamped exercises, and as time goes on it will take more and more pressure to yield any gains. There's only so much pressure you can put on your penis before things begin to become relatively dangerous... I don't necessarily have any case studies to base this off of, it's just my own personal opinion.
I personally feel a better girth routine would be one day of clamped work, one day of Supra Slammers....rinse, lather, and repeat as desired.