the theory is that you slowly disconnect cuz the symptoms of hyperventilation kick in slowly, it takes a few weeks for your over breathing to start causing symptoms. we speed up our breathing every time we panic, feel anxious, stress, 'till one day the brain just doesn't get enough oxygen any more and DP/DR feels more permenant. the panic/anxiety can one day stop, you could even take all kinds of anti-anxiety meds, but your body doesn't stop hyperventilation, cuz the brain is stuck triggering a fast breathing cycle, so dp/dr doesn't go away.
I know a lady (online) who cured herself of asthma completely in only 3 weeks of breathing exercises. now she's working on her DP next. both DP/DR and asthma are breathing problems.