Please, please do not thrown sticks for dogs.
I knew this but under the "it'll never happen to me" thought, I used to and my girl impaled herself on one and have massive damage to her mouth. Pease don't wait to learn this lesson the hard way.
If the pup has only been out twice, how are you socialising her?
Over exercising puppies can seriously damage their joints as they are not fully developed.
Unfortunately they don't know this so rest periods do need to be enforced.