In what cases might a test case be unnecessary?

• Exploratory testing.
• Ad hoc testing.
• Use case scenario testing, where the scenario description is sufficiently detailed.
• Testing small, simple changes or fixes.
• Testing in projects with very tight deadlines and limited documentation resources.
• Checklist-based testing.
• Intuitive testing.
• Agile methodology testing with a strong emphasis on automation and verbal communication.

It is important to understand that abandoning test cases does not mean abandoning planning and analysis. In these cases, other artifacts or approaches may be used.