Since its publication two years ago by a Dutch research team in the journal Science, the earlier finding had been used to encourage decision-makers to make "snap" decisions (for example, in the best-selling book Blink, by Malcolm Gladwell) or to leave complex choices to the powers of unconscious thought ("Sleep on it", Dijksterhuis et al., Science, 2006).

But in the new study, to be published in The Quarterly Journal of Experimental Psychology, scientists ran four experiments in which participants were presented with complex decisions and asked to choose the best option immediately ("blink"), after a period of conscious deliberation ("think"), or after a period of distraction ("sleep on it"), which is claimed to encourage "unconscious thought processes".

In all experiments, there was some evidence that conscious deliberation can lead to better choices and little evidence for superiority of choices made "unconsciously".

Saw you'd been spammed, and deserved a real comment
It's a great theory that sleep can help decision making, but one of the most critical factors can be a deadline.
Some people operate well under pressure. Or can be prepared to take a chance on something that may not otherwise have been tried because time is limited.
Sometimes a sleep has the effect of changing the subject which can show the decision in a new light.
Like when unable to remember a familiar name for 10 mins, forgetting, and 20 minutes later it jumps into your head You were looking in the wrong place(eg wrong first letter) Coffee works well

pop again for pokkets decision, i think it proves the point

My Dad used to say, "Let me sleep on this," when he wanted to make a careful choice of options.
I discovered the power of sleep to help solve problems, when I was trying to find a way to install kitchen wall cabinets without a helper. Checking "How-to" articles and TV "do-it-yourself" always featured a helper.
I went to bed, still stymied. To my surprise, when I awakened., I knew exactly how to do it. I got a couple of car-jacks out of the garage, set one at each end of the base cabinet counter, topped them with a sturdy two by twelve, cranked them up so the cabinets were 53 inches from the floor, and voila, it was easy. LOL
Doris

This actually shows that the synthetic approach works best, i.e. conscious effort (thinking) + unconscious processes (dreaming, intuition, etc).
I would say a person has to feed their brain some deliberate conscious input before expecting some profound complex solution to "dawn" on them. The history shows that most of the so called "intuitive" inventions came up after days of hard work and thought.