I do all mine at 40 yards, or more. If you shoot closer you can adjust things to suit your shooting method. I pull two strings between two posts, any distance over 4 feet apart, one string about 4 feet higher than the other one. Then I take a piece of my patterning paper about 4' by 4' with an extra 3" or 4" at the top and bottom, which are folded, and I hang it over the top string and use either tape or clothespins to hold it, and then I hook the bottom fold under the lower string and secure it, and you have your shooting area with no frame to get shot up. You may have to adjust the string a couple of times until you get the feel of it, so tie one string with un-tieable knots.
I have shot the string in half maybe 5 times in 45 years of doing it like that, but even when that happens that shot is still useable.
What could have happened... did.