Table-driven testing is a powerful technique used in Go to streamline the process of writing and organizing tests, making it easier to handle various cases and expectations without repetitive code. This approach allows developers to define a slice of test cases, each with its parameters and expected results, facilitating concise and clear tests. By implementing named test cases and leveraging subtests, the test output becomes more informative, helping to quickly identify which specific cases fail. Additionally, as the lesson highlights, recognizing the limitations of a simple guard-based approach to input validation prompts an upcoming revision of the algorithm to properly count words, taking into account edge cases such as empty strings, spaces, and newlines to ensure accurate functionality.