Grouped 'parent topic' volume double-counts and inflates your plan by 3x

Grouped 'parent topic' volume double-counts and inflates your plan by 3x
Some tools roll dozens of variants into one 'parent' volume. Pricing a page on that number overstates the prize. Across 500 parent groups:
— Parent reported volume ▇▇▇▇▇ index 100
— Sum of unique-intent children ▇▇▇ 58
— Overlap counted twice ▇▇ 42%
— Children with a different SERP than the parent ▇▇▇ 29%
The parent number is a marketing figure, not addressable demand for one URL.
The mistake: building a business case on the aggregated parent volume.
The fix: dedupe to unique-intent terms, drop children whose SERP differs from the parent, then sum what one page can actually capture.
Benchmark of the week: parent-topic volume overstates single-page addressable demand by about 42% in our sample.