Yes, it is recommended to allocate separate time slots for tackling challenging topics and revisiting areas you are more comfortable with in your PSIR study plan. This approach can be beneficial for several reasons:

1. Efficient time management:
By dividing your study time into separate slots for challenging topics and familiar areas, you can effectively manage your time and ensure that you give adequate attention to all aspects of the subject. This prevents you from spending excessive time on topics you are already comfortable with, while also ensuring that you allocate sufficient time to tackle difficult concepts.

2. Targeted learning:
Focusing on challenging topics during dedicated time slots allows you to give them your full attention. This enables you to delve deeper into complex concepts, engage in critical thinking, and develop a better understanding of the subject matter. By spending focused time on difficult areas, you can overcome any initial obstacles and gain a more comprehensive grasp of the material.

3. Consolidation of knowledge:
Revisiting areas you are more comfortable with during separate time slots helps reinforce your understanding and consolidate your knowledge. By reviewing previously learned material, you can solidify your grasp of the concepts, identify any gaps in your understanding, and connect different topics within the subject. This revision process enhances retention and improves your overall comprehension of the subject.

4. Balanced study approach:
Allocating separate time slots for challenging topics and revisiting familiar areas ensures a balanced study approach. This allows you to maintain a steady progress in your learning by continuously challenging yourself while also reinforcing and building upon existing knowledge. It prevents you from getting stuck on difficult topics for too long or becoming complacent with areas you are already comfortable with.

Conclusion:
In conclusion, allocating separate time slots for tackling challenging topics and revisiting areas you are more comfortable with can improve your study efficiency, enhance your understanding of complex concepts, consolidate your knowledge, and maintain a balanced approach to your PSIR preparation. By effectively managing your time and focusing on both challenging and familiar areas, you can optimize your learning and increase your chances of success in the UPSC exam.