In practice
The output is only as good as the seed. Feed it your best customers rather than all leads, or you will scale the profile of people who never bought.
Refresh the seed list on a schedule; a lookalike built on last year's buyers slowly drifts away from the market you have now.
Why it matters
It is the main way first-party data turns into reach — the CRM stops being a sales asset and becomes a media one.
Related terms