I'm normally more of a planner but some of my best decisions have been made on a whim over the course of my life. I think some situations definitely require a lot of pondering and due diligence but others are better done on the fly as the outcome isn't potentially some life or death situation (not in a literal sense but I'm sure you catch my drift).

The hiring example you gave was a good one as interviews never show a person's true talents, temperament in tough situations, etc so it's better to do so quickly in many cases. Interviewing many applicants is also time consuming and time is money, especially for someone with multiple business ventures who is busy most of the time. Why waste that precious time interviewing a lot of people and agonizing over the decision when you could pull the trigger and get a real sense of how the new employee will perform.