Conventionally Dependent Origination is considered in interpretations, to be over 3 lifetimes. Personally I prefer the momentary or one lifetime version. However I won't go into that because there are plenty of references in the Theravada forum. It's my opinion that a genuine experiential understanding of sunnata (emptiness) is arrived at not through complex debate, nor through spacing out in an emptiness la-la land, but through simple analysis, together with regular meditation practice - and the purification of mental obscurations...... To quote Ajahn Buddhadasa: "If at any moment any person at all has a mind empty of grasping at and clinging to 'I' and 'mine', even if it is only for an instant, it means that the mind has realized emptiness. It is pure, radiant and at peace. It is one and the same thing as the heart of the Buddha, the Dhamma and the Sangha. Thus at any moment that one has a mind empty in this way one has taken refuge, one has reached the Triple Gem." http://www.budsas.org/ebud/ebdha196.htm