I remember reading something about breathing deeply through your nose is like turbocharging. It sends more air into your lungs and by filling out your lungs and using your diaphragm, you can take fewer breaths, but get more oxygen. It does act as a speed governor because at some point, your breathing can't keep up. That's when I start breathing through my mouth and nose at the same time and still try to breathe in deeply. Didn't know about the long exhales so I'll give that a shot tonight.