I used bully sticks with Sophie, and had no issues with them. I started giving them to her when she was about 11 weeks old. I'd let her chew them until they were about half the original size, maybe about 5 inches, as I did want to take a chance of her swallowing them whole at that point. The bigger she got, the quicker she could go through one. I finally stopped using them as they just weren't cost effective. There were other things that were cheaper, and lasted longer. Cow hooves, pig ears, retriever rolls, antlers, stuffed kongs, marrow bones all lasted longer.
Not all brands of bully sticks are created equal. I can't remember which brands were best, but some definately last longer than others. Sophie was a heavy power chewer, so your mileage may vary. Bruce has been a completely different story. He's not a big chewer, or anywhere near as active as Sophie was, so I don't constantly have to stick something in his mouth. He likes ropes, nylabones, and Sophie's old bones to chew. Of course he is just beginning to teethe, so that could all change!