Introduction:
When it comes to preparing for the Economics Optional subject for the UPSC exam, students often wonder whether they should revise from multiple sources or stick to one. Both approaches have their own advantages and disadvantages, and the choice ultimately depends on individual preferences and learning styles. In this detailed response, we will explore the pros and cons of both approaches to help you make an informed decision.

Revising from Multiple Sources:
1. Exposure to Different Perspectives: One of the major advantages of revising from multiple sources is that it provides you with a broader understanding of the subject. Different authors and sources may present concepts, theories, and examples in diverse ways, allowing you to grasp the subject matter from various angles.
2. Comprehensive Coverage: By referring to multiple sources, you can ensure comprehensive coverage of the Economics Optional syllabus. Each source may have its own unique set of topics, case studies, and illustrations, which can help you gain a holistic understanding of the subject.
3. Enhanced Analytical Skills: Studying from multiple sources exposes you to different analytical frameworks and methodologies. This can sharpen your critical thinking abilities and equip you with a diverse range of tools to approach economic problems, thereby enhancing your overall problem-solving skills.
4. Preparation for Unpredictable Questions: UPSC is known for asking unpredictable and unconventional questions. By revising from multiple sources, you increase your chances of encountering a wide range of questions and scenarios. This can better prepare you for handling unexpected questions during the exam.

Sticking to One Source:
1. Consolidated Knowledge: When you stick to one source, you have the advantage of consolidating your knowledge and developing a deeper understanding of the subject. The repetition of concepts, theories, and examples from the same source can reinforce your learning and help you retain information more effectively.
2. Time and Resource Management: Revising from multiple sources can be time-consuming and overwhelming. By sticking to one source, you can save time and focus on understanding and revising the content thoroughly. This approach also helps you manage your study resources more efficiently.
3. Consistency in Approach: Each author may have their own unique style and approach to presenting the subject matter. By sticking to one source, you can develop familiarity with the author's style and thought process, allowing you to follow the content more easily and maintain consistency in your approach.

Conclusion:
In conclusion, the decision to revise from multiple sources or stick to one ultimately depends on your personal preferences and learning style. Revising from multiple sources can provide you with a broader perspective, comprehensive coverage, enhanced analytical skills, and better preparation for unpredictable questions. On the other hand, sticking to one source allows for consolidated knowledge, effective time and resource management, and consistency in approach. It is important to strike a balance between the two approaches and choose the one that best suits your needs and goals. Remember to focus on understanding the concepts thoroughly, practicing with past papers, and seeking guidance from mentors or experts to excel in the Economics Optional subject.