Young dogs much like babies sleep a lot during the day especially if the dog is taken out for regular excercise. If the dog is eating well, pooping and urinating normally and seems content, what is there to concern yourself with? I would hazard a guess that my two dogs sleep on average six hours a day and then another eight to nine hours at night. Enjoy your dog! Good luck
It depends on it's activity level. If you exercise it properly and it is rather playful than it may take longer and more frequent naps due to the fact that it is properly exercised,and is using up a lot of energy. If you have a lazy pit bull, and it sleeps a lot then it is most likely one of two things... It is lazy, just it's personality. Or maybe it has low sugar levels. Make sure the puppy is getting proper nutrition. You can still mix some puppy formula with their puppy chow, or meat baby food is a cheaper option to mix with their puppy chow. However you need to avoid pork baby food as this is not always good for a puppy's stomach.