The dominant coaching consensus — articulated by ClearIAS, Insights on India, Sleepy Classes, and GS Score — is an integrated, simultaneous approach, not a sequential one.

The core logic: Prelims and Mains share roughly 70 to 80 percent of the same content. The difference is not in what you study, but how you engage with it — Prelims demands precise factual recall for MCQ elimination, while Mains demands analytical depth and structured writing. Studying the same topic with both lenses from the beginning is more efficient than treating them as two separate exams.

The recommended model for a first-timer:

• Months 1-9: Mains-centric preparation — build conceptual depth, cover the full GS syllabus, write answers, cover optional. Do not ignore Prelims; solve sectional tests on completed topics.
• Months 10-12 (final 3-4 months before Prelims): Shift to Prelims-specific mode — full-length mocks, CSAT practice, MCQ techniques, rapid factual revision, PYQ analysis.

The risk of strict Prelims-first approach: Spending 4 to 5 months exclusively on Prelims means your Mains preparation stalls, answer writing practice stops, and you must restart from zero if you clear Prelims — which leaves only 3 months for Mains, an almost impossible timeline for a first-timer.

Important caveat: The last 6 weeks before Prelims should be almost entirely Prelims-focused. Do not dilute this phase with new Mains topics.