Myth: Country-level geo rules are precise enough

Myth: Country-level geo rules are precise enough

The belief: route by country code and you've covered geo.

The correction: payout and conversion swing inside a country — tier-1 cities vs rural, English vs regional language, carrier vs WiFi. Country-only routing averages winners and losers into mush.

Framework — geo granularity ladder:

— Step 1: Start at country. Baseline only.
— Step 2: Split by region/state where you have 500+ clicks to justify it.
— Step 3: Add language as a separate axis (browser locale, not geo).
— Step 4: Add connection type (mobile carrier vs WiFi) for offers that care.

Checklist:
☐ Each country with volume reviewed for internal splits
☐ Language treated separately from country
☐ No split created below 500 clicks (avoids noise)

Repeat the granularity review monthly.