What is the 3-second rule in finance?

Detailed Explanation

It is a deliberate pause between deciding to spend or invest and actually doing it. The purpose is not the length of the pause — three seconds is short enough that it costs nothing and is therefore actually used. The purpose is to break the automatic path from impulse to action, which is where most avoidable financial mistakes are made. In that gap you ask one question: does this move me toward a goal I have already written down? If the answer is not obvious, the decision deserves more than three seconds.