The last hack contest I read about, the dood (Miller) had it all worked out before he ever attended the PWN2OWN contest. Here is a quote.
"I can't talk about the details of the vulnerability, but it was a Mac, fully patched, with Safari, fully patched," said Miller on Wednesday, not long after he had won the prize. "It probably took five or 10 seconds." He confirmed that he had researched and written the exploit before he arrived at the challenge."
In other words he worked with it for days, weeks even months then came and did it in the short time. He just did not walk in off the street and hack a mac in 10 seconds.