When Akari considers whether she should work one more hour, she is applying the principle.

When Akari weighs the money she will earn from working overtime against what she gives up to work the extra hours, she is applying the principle.

If Akari decides to work the extra hours because she does not think any overtime will be offered in the near future, she is applying the principle.

If Akari decides to work overtime because her next best alternative is watching TV at home, she is applying the principle.