Two things:
First, regarding how many bullysticks per week - Geoff gets free access to as many as he wants. We have several lying around the house and he just helps himself whenever he feels like it - usually almost daily before bedtime. His favorites are the 12" braided ones, and I think he usually averages about 3 a week.
Second, Bullies don't go bad, at least the ones we buy don't.
As I mentioned before, at any given time we have three or four bullysticks at various stages of "finished" laying around the house. Geoff just picks and chooses his favore whenever he feels like it. Never had problem.
Out of curiosity - why do you think they would go bad, and how? The bullies we buy don't need to be stored in a freezer and do not come in any specific packaging. They can lay around for months before being fed to the dog. And they are no different when the dog has chewed on one end than they are before they've been chewed on - so why would one chewed end make a bullystick go bad?