All rules have exception.
This self-paradoxical epigram is very famous. We must always be careful to decide whether the rule should be adapted to current situation. This work is hardly done by a computer. Be flexible. Otherwise we would be replaced to computer easily.
However, the rule that include too much exception in it will not work correctly.
Imagine a driveway in Japan. Regulated speed is 40 km/h in a city area. But nobody adhere this regulation. If you handle a car with 40km/h, you would be blamed by any other drivers. On the other hand, maximum speed of bicycle is not limited. So you can ride a bicycle with over 200 km/h legitimately, if possible!
It is an example that exception may overcome the rule.
In general, the rule or legislation is established to protect interest or safety of weak people. So when people other than predicted are adapted to the rule, the intention of the rule would be twisted. It is sometimes criticized that rich people get advantage of extra financial aid for medicine. It means that redistribution of estate that is one of function of government is abused.
In medical care field there is a lot of exception. It is quite natural since human bodies vary one another. Moreover we are always annoyed by personal information protection policy. As a principle, we are not allowed to tell information of the patient to other people, even their family without permission of the patient. But this rule is hardly adhered. When the patient cannot visit hospital for some reason, we have to consult his or her family, even prescribe some medicine to deliver it to the patient. This kind of behavior is not so evil, but we must be aware to our behavior and the meaning of it in legal context.
In my sense, rate of exception should be lower than 5%. And when the rate reached to 30%, the system itself will be collapsed. Before the critical point we should examine the rule and change it with correct method.