Crossing over your thoughts.
There exists a very thin line between smart and over-smart. Smart one gives the result while over-smart gives the vision of the result. A smart employee completes the given work within time with fine quality but an over-smart employee portrays completeness of the work within time.
Similarly there is a very thin line between decision making and rational decision making. Decisions in life are rarely black and white but usually involve shades of gray.
What to wear to office does not involve a decision between to wear a dress or a party wear but includes a decision between what colors of shirt to be worn. During the medieval period, sovereigns used to have a thorough plan and used knowledge management to have an effective strategy for winning. Rational thinking was the key to achieve this. Rational thinking results in a desired output achieved within limits.
As these examples show, individuals and firms can make better decisions by thinking at the margin. A rational decision maker takes an action if and only if the marginal benefit of the action exceeds the marginal cost. It guides throughout the process for the excellence and attainable targets.
The case study approach helps to decide what the margin for the decision to be taken is. Once the margin is known it becomes a cake walk to make the company decisions.