Using LIMIT in #BigQuery does not save costs as it doesn't affect the amount of data processed, only the number of results returned. However, LIMIT is useful for:

• Validating assumptions: For example, checking for duplicate records. Finding even one duplicate indicates a problem.
• Query efficiency: On large tables, using LIMIT can reduce query execution time, saving you time.

If no results are returned with LIMIT, it validates the initial hypothesis. Note that LIMIT can impact performance in specific cases, as discussed in the comments.