I must say I'm not advocating snap judgement at all. I just think it is very common (as Kahnemann states). What he states as an ideal doesn't necessarily make an awful lot of difference in many situations; the snap judgement can very often be the same as the careful one (though external factors that partly force/aid preselection bias things greatly in this respect).
Do you have any evidence at all to back this up? In general, people think they are much better at making decisions than they are, and unless you actually measure things empirically and track false positives/negatives, you are likely to fool yourself.