Nothing is guaranteed when talking blood trails, but something that will generally exit with a decent-sized hole does increase your odds of finding your deer more easily if it runs. You still have to put it in the right spot (high lungs may not leak), and even then, you'll have oddball instances where you just don't get the leakage you think you should. Having said that, the law of averages says that wrecked vitals and a good exit will help out over the long run.
