What it changes
Who can pull it
What it looks like institutionally
The instinct to "clear out old records" treats deletion as cleanup. In published PAN runs it is the opposite: removing records without reading them raises the contaminated SHARE of the record system, because the benign entries being deleted were diluting the bad ones. A content-blind purge strips the dilution and leaves a denser pool of error behind — a backfire, not a scrub.
Only content-aware decontamination — audit each record, correct or retire the ones that are actually wrong — reliably reduces contamination. And even that is bounded: an optimistic anchor near 96% token accuracy falls away on hard content, so decontamination is a partial control that must be planned as a range, not a guarantee.
The practice, then, is disciplined: never delete by age or volume alone; read before you remove; label what you cannot yet verify (see Provenance labeling) rather than purging it blind.
Addresses: Content-blind record removal · Contaminated-share inflation. Test a version of this lever in the PAN Lab.