Sufficient Level of Examination?

Do we simply go with our gut, or do we take a step back and leverage our reasoning? The interesting thing to note here is as Daniel Kahneman points out, we have two parts of our mind. The one that thinks fast, and the other slow. The fast mind tells us that 2 + 2 = 4. However, a slow mind can calculate 284 + 549. So for certain simple questions, we can answer quickly, but for more complex issues, our slow mind needs to come into play. But again, to the first point, we must leverage our mind as a tool, not a master.