How do you identify if a result in a decision rule cannot be returned?

Creating a new rule in Pega Platform is typically done to define a new behavior or functionality in the application, which can then be reused as needed. In the given scenario, a designer is reusing a UI section every time the same behavior is needed in the application. By creating a new rule for the UI section, the designer can ensure consistent behavior and avoid duplicating effort.
For which use case do you create a new rule in a Pega Platform application?

Which piece of application content do you localize by using a Field Value rule?

To qualify for an instant loan, an applicant must be older than 21 and have a monthly income of atleast USD2000. How do you enforce these restrictions?

A company often receives multiple IT tickets for the same issue, such as ''the office Wi-Fi is down.You configure Search duplicate cases step to identify duplicate IT tickets. What is the basic condition for the Search duplicate cases step?