Dogs learned quickly in the wild that the best way to store food for your own use is to eat it right now and eat as much as you can. Hence, dogs will often eat as long as there is food available, even to the point where surgical emptying of the stomach is necessary. Thus you should never let your dog has as much as she wants.
And yes, as syz says, there are potential risks if your dog bites off huge chunks of rawhide and swallows them whole, or if you are giving her lots of rawhide.
Since pit bulls and puppies both love to chew, and pit bull puppies LOVE to chew, you might consider having several items available for chewing. Our pit bull and our American Bulldog both enjoy it when I tuck a bit of cheese or peanut butter inside a couple of giant kongs ( the biggest black ones). Nylabone makes a line of "Big Chew for Big Dogs" toys that last a long time also. ( a selection can be seen at http://www.bigtimedogtoys.net/ultra-tough-toys.html - we buy ours at PetSmart). We also have some heavy-duty knotted rope toys for pulling (bully breeds love to play tug of war). We also get the giant "knuckle bones" for when we will be home to supervise. They can spend several hours on one of these.
By rotating these toys we help keep the dogs from getting bored and trying to eat the furniture. We also have set up certain situations when a chew toy will be offered so the dogs know when to ask. Typically they get something after dinner and the last out of the day so they can settle down and start working on letting us sleep. They know this and are ready typically at 10 pm for their treat.