I haven't had any problem with mold or stink or matting. But then, I don't get any water in the bedding. And the chickens are constantly digging in it, mixing it up. And now that I have a system I don't feel that I'm putting any real time into the prep for the cardboard.
I've had the cardboard in a stall since late summer, and the coop since the chickens moved inside about a month ago. The stall is used occasionally to house 2 llamas overnight (when they'll be wanted for something in the morning) and for a horse every so often from a few minutes to a few hours at a time. And now that we have snow the stall is the daytime run for the chickens because I never got an outdoor covered run built.
In an normal winter I'd have to say I can't tell about stink because we'd be in the deep freeze by now, but winter just can't seem to settle in to stay this year and we just had a string of above-freezing days and the barn smells fine. (The coop is inside the barn.)
We used pine pellets the last two winters when the llamas spent their nights in the stall (and days outside with the horses; this year they have their own area so they're outside 24/7). That was
dusty. And the barn smelled of llama. Not that it wouldn't smell with paper if the llamas were in, but the pine didn't prevent that. At least so far, in my situation, I'm really not seeing any downside to the cardboard compared to what I've used before.
EDIT: thought of 3 points to add overnight:
- I would definitely agree with @
catballou in a place that gets wet. My pigeon aviary gets wind-blown rain and snow through the hardware-cloth sides, plus they take water baths in a shallow tray (and splash it everywere), so pine pellets work there. My husband also puts down pellets (due to their greater absorbency) in the "litter box" corner of the stall when the llamas will be in, as they always go (pee and poop) in the same place. When cleaning up after a horse that has peed, all the wet bedding (of whatever sort) gets shoveled out, and I don't see much difference between sawdust or shavings and paper/cardboard shreds.
- In my previous horse-keeping life (teen in '70s), before the current market for wood waste products, we (i.e. my mom!) could get truckloads of coarse sawdust super cheap and I got used to deep bedding. Now that I have horses again, I was skimping the last few years when we bought bedding by the bag from Tractor Supply. I'm so thrilled that I've found a free source of acceptable bedding so I can put in a good depth of bedding (at this point probably about 4") and I'm sure my horse appreciated it 2 months ago when she spent several days inside with what turned out to be a brewing abscess.
- Cardboard put through a microshredder (which makes very small kind of kinked shreds) has more texture than paper from a standard crosscut shredder, plus brown paper is more absorbent than white printer paper, so the source material may affect our relative experiences.