Why it matters: seemingly independent rows can contain the same customer, template or derived answer.
A strong answer should cover: source grouping, near-duplicates, temporal ordering, repeated tuning, synthetic lineage and supplier access. Ask for an inspection procedure and what it cannot detect. Group-based splitting is a mechanism, not a cleanliness certificate.
Follow-up: “Would you redesign the test for new customers, future traffic or unseen templates—and why?” Record which commercial claim each split can support.
Interview status: Not yet interviewed.