I won't use my shredded paper in my brooder as I don't want, and my baby chicks will eat the paper. Don't want them to start with digestive problems. Also slippage.I found an interesting YouTube video on a comparison of different litter material used for brooder. One of the litter options was shredded paper. She had 5 different categories to consider. The shredded paper came out as the #1 preference for her chicks to sleep in, which was one category. I guess you can buy shredded paper in compressed plastic wrapped bales, which is what she did, but I don't know why you could not just use your own paper shreds you make at home. Anyway, she spent good money on buying shredded paper bales and that knocked it down in the cost category compared to the low cost she paid for sand. I think if she had been using free paper sheds, maybe paper would have come out top in that category, too.
Anyway, interesting to see a comparison of different litter methods to use for the chicks.
Purchased shredded paper may have a larger shred and different paper. Though, I have not done cardboard and may try with my littles in the future.