We are obeying rules often unconsciously which have been established in our mind. These rules are usually proper for maintaining our daily life effectively.
However, there are some opportunities to change the rule deliberately. The reasons are various; in some cases the rule is outdated. Otherwise, you can no more adhere the rule.
For example, I wait five minutes before calling the counterpart when he or she does not appear at the meeting point. The five minutes rule is common, I believe. In most cases, I need not ring or email because they are delayed for only a couple of minutes.
But, in some cases, the few minutes become critical. Also, there is a possibility that I misunderstand the meeting time or place. In such an occasion, the faster I start to reschedule, the less the meeting time will be wasted.
Then, I have changed my rule: when I miss the counterpart, I will take a call immediately.
Maybe it is a small change. But the life is a pile of small changes.