A referral report lists two thousand URLs. It looks like broad reach and usually is not — most of those URLs come from a handful of domains.
Reducing to sites
Strip the paths and count occurrences per domain. Two thousand referring URLs frequently resolve to under a hundred sites, with the top five accounting for most of the traffic.
Concentration is the finding
If three domains send seventy per cent of referral traffic, those are relationships worth actively maintaining rather than treating as background. It also means the referral channel is fragile — losing one placement removes a large share of it.
Check the long tail before dismissing it
Domains sending small volumes sometimes convert far better than the high-volume ones, because the context is more relevant. Look at conversion rate per domain, not just sessions, before deciding where to invest.
Try it: Strip URL Path (Keep Domain Only) on SeoWolf's Notepad.