I would never waste any rounds, period. If you want to intimidate with noise, try shouting, "I've called 911, go away!"
If I'm a bad guy I might be thinking I know more that I really do. I might decide to come through the door after 8+ wasted rounds thinking you are not serious about shooting me. Now you must rely on your ability to make stopping shots under extremely stressful conditions.
You might want to rethink your plan.