For User Acceptance Testing (UAT) to be efficient, it's crucial to have clear and agreed-upon acceptance criteria with the customer. This ensures that both parties have a mutual understanding of what constitutes a successful test outcome. Defining these criteria upfront helps streamline the testing process, as it focuses efforts on verifying that the system meets the business requirements and expectations. While the specific document reference for this answer isn't available in the provided Salesforce Revenue Cloud documents, this approach is awidely recognized best practice in UAT planning and execution in software development and implementation projects.