Introduction:
Solving previous years' papers for UPSC Botany optional is an important part of the preparation process. It helps in familiarizing oneself with the exam pattern, understanding the type of questions asked, and improving time management skills. However, the question of whether to solve these papers as full-length mock tests or in small sections depends on various factors.

Full-length mock tests:
Solving previous years' papers as full-length mock tests has several advantages:

1. Time management: Full-length mock tests help in developing the ability to manage time effectively during the actual exam. It gives a realistic experience of the time constraints and enables candidates to strategize their approach accordingly.

2. Exam simulation: Solving the entire paper in one go simulates the actual exam environment, making candidates accustomed to the pressure and stress they might experience during the UPSC Botany optional exam.

3. Identifying weak areas: Attempting the full paper allows candidates to identify their weak areas and focus on them during their preparation. It helps in assessing overall performance and understanding which topics require more attention.

4. Building stamina: Solving a full-length paper requires mental stamina and concentration. Regular practice enhances the ability to stay focused for an extended period, which is crucial for performing well in the UPSC Botany optional exam.

Small sections:
On the other hand, solving previous years' papers in small sections can also be beneficial:

1. Topic-wise revision: By dividing the paper into smaller sections based on different topics, candidates can revise specific areas of the syllabus in a focused manner. It allows for a deeper understanding and analysis of each subject.

2. Incremental learning: Solving papers in small sections helps candidates gradually build their knowledge and confidence. It allows for a step-by-step approach, ensuring that all topics are covered thoroughly.

3. Effective time utilization: Some candidates may find it difficult to allocate a dedicated time slot for solving full-length mock tests. In such cases, solving papers in small sections can be a more manageable and efficient way to utilize available study time.

4. Flexibility: Solving papers in small sections provides the flexibility to focus on specific topics as per individual needs. It allows candidates to customize their preparation strategy and allocate more time to challenging areas.

Conclusion:
Both approaches have their merits, and the choice between solving previous years' papers as full-length mock tests or in small sections depends on the candidate's preferences, study schedule, and individual strengths and weaknesses. It is advisable to strike a balance between the two approaches and incorporate them into the overall preparation strategy. Regular practice, thorough analysis of answers, and timely revision are key to achieving success in the UPSC Botany optional exam.