The system also provides a reason for followers to be "supererogatory" In ethics, "supererogatory......indicates an act that is good but not morally required to be done" [4].
An example is if a man hijacked a bus of students and said if one person dies, then he will let everyone free [3].
The teacher who believes in deontology would volunteer to die because he feels it's his obligation to protect the safety of his students, and many others would view his act as "superergatory" because he is exceeding his duty to protect his students [3]