In his mega-popular book Blink, Malcolm Gladwell centers his thesis on the claim (supported abundantly) that experts come to the point where “they just know.” They develop intuition, based on diligent practice (in another of his best-sellers, Gladwell says “10,000 hours” of concentrated practice is necessary to achieve expertise in any endeavor). So experts get the answer without having to go through a step-by-step process of analysis.
Psychologists call this approach “top-down” information processing, as opposed to “bottom-up” processing. They also use the term “fast and frugal heuristics” to capture the phenomenon of quickly getting the answer, assessing the probabilities, without having to do math. Based on experience, you just know, faster than you possibly could via painstaking, rational analysis.