^^ It's I think generally exhausting to really try to wake up after every sleep cycle constantly, but once in a while, maybe for a month, or a few weeks at a time, in between really resting up, it's worth trying, in order to really see at what time your best dreaming occurs. In the range of 5.5-6h for me, too, is where I get a lot of vividness and long coherent "I'm there" dreams. You can also wrack up an amazing amount of recalled dreams this way.