What is a common issue with use cases in terms of completeness?

Use cases are designed to capture the interactions between users and the system, illustrating how the system responds to various inputs. A common issue regarding their completeness is that they may not describe all transaction paths. This can occur if the use case fails to account for alternative scenarios, exceptions, or different user roles that might affect how a process unfolds.

When not all transaction paths are clearly defined, it can lead to misunderstandings of the system's requirements. This lack of comprehensiveness can result in critical aspects of the user experience being overlooked during the development process. Therefore, ensuring that use cases cover all potential paths is essential for capturing the full functionality required by stakeholders and guaranteeing that the system behaves as expected under all conditions.

The other options address important concerns, such as structure, action overload, and diagram accuracy, but they don’t specifically focus on this completeness issue related to capturing all possible transaction paths.