With possibly just a few thousand Few in the whole of Three Seas, scattered so thinly, it would be a task of tremendous importance and extreme difficulty, since the very survival of Schools hangs on it. Young children with capacity for sorcery don't bear a Mark, so how do Schools identify them?
Achamian recalls a specific moment in childhood when he realized it, and was later taken away by a Mandate Pederasik who claimed Achamian was a "bright child, with great promise" (paraphrasing). But how was he found and identified as one of the Few? Is there something else essential that sticks out about them, aside from Mark, before they become sorcerers? Or is there testing involved? Schools' recruiters traveling around on the lookout for "bright children" and administering tests ala Kellhus activating Wathi doll or Mimara holding Achamian's Surillic Point without being sorcerers themselves at the time?