Case: splitting one sitemap into 12 by template exposed a 40%-indexed dead zone

Case: splitting one sitemap into 12 by template exposed a 40%-indexed dead zone

A single 200,000-URL sitemap reported '74% indexed' — useless for diagnosis. SOP:

— Step 1 (ops): split the sitemap by template type into 12 files, max 20k URLs each. Gate: one sitemap per page template.
— Step 2 (analyst): read per-sitemap index coverage in Search Console.
— Step 3 (analyst): found 11 templates at 85-94% indexed, but the 'tag' template at 40% — dragging the average.
— Step 4 (strategy): noindexed and de-listed the tag template entirely.

Outcome: removing 28,000 tag URLs raised sitewide indexation to 89% and freed crawl for money pages. Diagnosis took one afternoon once sitemaps were segmented.

Guardrail: segment sitemaps by template so coverage data is actionable, not an average.

Ship gate: don't publish until all boxes are checked.