I almost never see a joint that keeps burning when nobody's hitting it. I think it's the filter that makes the difference between a cig and a J. Burning constantly, and J and a bowl are about equally efficient THC delivery systems. The bowl has the advantage when you have to relight it. You waste less weed without having to get the paper hot too. But they both go out about equally, maybe even giving the joint an advantage since it has a smaller fire that has to go out. So yeah, they're about even.