The immutability argument resonates strongly for regulatory filings. I work with XBRL data from Japanese government disclosures, where historical documents are frozen the moment they're accepted by the regulator—the 2019 annual report for a company never changes.

The model that's worked: append-only ingestion with a submitted_at field, treating corrections as new document submissions (which is actually how the regulator models them too—amended filings get new document IDs). Downstream consumers query as-of a timestamp, which makes the cross-team pattern trivial: everyone reads from the same immutable ledger and gets a consistent snapshot.

The hard case is when a company resubmits corrected data for prior periods. We model this as new records with amendment references rather than in-place updates, preserving the immutability guarantee but requiring consumers to be aware of the supersession chain.

Curious how this scales to domains with higher correction rates than regulatory filings—for us, amendments are maybe 2-3% of total submissions, which is manageable. What's the correction rate where the immutable model starts to break down practically?