I use it permanently. It doesn't mold, unless you plan on leaving it submerged in water 24/7. It's not dusty at all, and when soaked it breaks down like toilet paper, not like mouthfuls of wood splinters or dirt. I have it mixed in with the spaghum moss in the humid hide, and I literally dump water on it and it doesn't mold. All I do is fluff it up every 3 or so weeks because it packs down solid.
Most people don't like that it's not "natural", which is the worst argument you can make when your snake sleeps in a cut Styrofoam bowl with a dog water bowl.
The ONLY real issue is that the carefresh brand released some that I think had baking soda in it? I haven't seen anything else on that, they said they discontinued it after reports of small animal deaths (Baking soda is toxic to them) I stick with the off brands.