Never, which is the uncomfortable version of the answer. One cleanup in week one, nothing after. The cadence question is the one I'd redirect, though. Stale sources were a retrieval bug, not a freshness bug: date filter plus an explicit allowlist, ten minutes, and the corpus could stay as messy as it liked. Scheduling refreshes would have bought trustworthy output by making the upkeep term worse, which is the thing the arithmetic was already losing to.