Well, honey, I must say that I have to pace myself because those suckers are thick and if your blade is not sharp, it is a LOT of work!
I usually open most of the seams (sometimes leave the double stitched one for decorative effect) because it will give me at least another inch in width, and sometimes a nice colour variation. But there is really no way of making it any easier than to keep a sharp blade and just do a bit at a time. That is why I rarely do rag quilts from denim--just too darned thick and hard to snip!!