What is one reason a sledge can become unusable?

A rounded head on a sledge can make it unusable because the design and shape of the head are crucial for the tool's effectiveness. Ideally, a sledge's head should be flat and sharply defined, allowing it to deliver focused force onto a targeted surface. If the head becomes rounded due to wear or impact, it may not strike properly, reducing its ability to transmit energy effectively and making it less effective for tasks such as driving stakes or breaking rocks. This reduction in function can lead to safety issues as well, as the tool might slip off the target or fail to perform its intended use, which is essential for an outside lineman's work.

Considerations around a painted handle or excessive weight generally do not pose immediate concerns regarding usability; for instance, a painted handle could still provide sufficient grip, while excessive weight may affect maneuverability rather than functionality. A firm grip is also a desirable characteristic. Thus, the rounded head is the most critical factor leading to a sledge's obsolescence in its intended role.