Yes, the previous years question papers of UPSC Mathematics optional subject are useful for time management. Here's how:

1. Familiarity with Exam Pattern:
- The previous years question papers give you an idea about the exam pattern, the type of questions asked, and the marking scheme.
- By going through these papers, you can understand the distribution of marks for different topics and prepare accordingly.
- This helps you allocate your time effectively during the exam, giving more attention to the topics that carry higher marks.

2. Time Allocation:
- Solving previous years question papers allows you to practice time management skills.
- You can time yourself while solving the papers to simulate the actual exam conditions.
- This helps you understand how much time you need to allocate for each question and section, ensuring that you complete the paper within the given time frame.

3. Identifying Important Topics:
- Going through the previous years' papers helps you identify the important topics that are frequently asked in the exam.
- This allows you to prioritize your preparation and spend more time on these topics, increasing your chances of scoring well in the exam.

4. Enhancing Speed and Accuracy:
- Solving previous years' papers regularly improves your speed and accuracy in solving mathematical problems.
- You become familiar with the types of calculations, tricks, and shortcuts required to solve the questions quickly.
- This helps you save time during the exam, enabling you to attempt more questions and increase your chances of scoring higher.

5. Confidence Boost:
- By solving previous years' papers, you gain confidence in your preparation and become familiar with the exam format.
- This reduces exam anxiety and helps you perform better on the day of the exam.

Conclusion:
Solving previous years question papers of UPSC Mathematics optional subject is indeed useful for time management. It helps you understand the exam pattern, allocate your time effectively, identify important topics, enhance speed and accuracy, and boost your confidence. Regular practice of these papers will significantly improve your performance in the UPSC Mathematics optional exam.