One of my friends that is a traditional shooter uses the shrink wrap in four of his targets. If you are using carbons it they may be creating too much friction on the wrap causing some minor melting.
I use a Block target with supports on the top and bottom, then 2 ratchet straps to compress it. I also have a Black Hole, which is like throwing money in a black hole, useless for carbons. Then for broadheads I have 5 - 4' tall dock floats. The carbons are a little fast for the Styrofoam blocks as I have to scrape the melted stuff of the arrow once in a while. But the Block is on it's 7th year. I don't shoot broadheads at it.