Introduction:
The ideal time duration for completing the Economics Optional syllabus depends on various factors such as the candidate's prior knowledge, study schedule, and the availability of resources. However, on average, it is recommended to allocate around 4-6 months for a comprehensive preparation of the syllabus.

Understanding the Syllabus:
Before diving into the time duration, it is crucial to have a clear understanding of the Economics Optional syllabus. The syllabus is divided into two papers, Paper 1 and Paper 2, each covering different aspects of economics. Paper 1 focuses on microeconomics and macroeconomics, while Paper 2 includes Indian economy, international economics, and development economics.

Time Allocation:
To effectively cover the entire syllabus, it is advisable to allocate time as follows:

1. Paper 1:
- Microeconomics: 2-3 weeks
- Macroeconomics: 2-3 weeks

2. Paper 2:
- Indian Economy: 3-4 weeks
- International Economics: 2-3 weeks
- Development Economics: 2-3 weeks

Total Time:
Considering the above time allocation, the total time required to complete the Economics Optional syllabus would be around 4-6 months. However, this duration may vary depending on the candidate's pace of learning and the depth of understanding required.

Study Plan:
It is essential to create a well-structured study plan to make the most of the allocated time. Here is a suggested study plan for Economics Optional:

1. Preliminary Understanding:
- Start by reading the NCERT textbooks on microeconomics, macroeconomics, and Indian economy to gain a preliminary understanding of the concepts.
- This can be completed in the first few weeks.

2. In-depth Study:
- Once the basic concepts are clear, move on to standard reference books like "Microeconomics" by Pindyck and Rubinfeld, "Macroeconomics" by Dornbusch and Fischer, and "Indian Economy" by Ramesh Singh.
- Read and understand each topic thoroughly, making notes for revision purposes.
- This process should take around 3-4 months.

3. Practice and Revision:
- After completing the syllabus, allocate time for solving previous year question papers and mock tests.
- Regularly revise the topics, focusing on areas that need improvement.
- This stage should be ongoing throughout the preparation period.

Conclusion:
In conclusion, allocating around 4-6 months for completing the Economics Optional syllabus is considered ideal. However, it is important to customize the study plan according to individual strengths and weaknesses. Consistent effort, regular revision, and solving practice questions are key to mastering the subject and achieving success in the UPSC examination.