When uncertain about lifespan, expire at 3 months not 1…

Err toward shorter expiration windows when uncertain about information lifespan, setting expiration at 3 months if unsure rather than 1 year, because expired items can be renewed while accumulated stale information cannot be easily detected.

When This Fires

When assigning an expiration date (Tag time-sensitive information with explicit expiration…) and unsure about the information's lifespan
When debating between "it might last a year" and "it might last three months"
When building default expiration policies for categories of information
Complements Tag time-sensitive information with explicit expiration… (expiration at capture) with the decision heuristic for uncertain cases

Common Failure Mode

Optimistic expiration: "This is probably valid for at least a year, so I'll set expiration to December." But "probably" means you're uncertain, and uncertain + long expiration = high risk of silent staleness. The item quietly becomes outdated by April, but the expiration flag won't surface it until December — 8 months of potential stale-information harm.

The Protocol

(1) When assigning an expiration date, ask: "Am I confident about this information's lifespan?" (2) If confident → set expiration to the known end-of-validity date. (3) If uncertain → default to 3 months from today. This triggers a review in 3 months where you'll reassess with fresh information. (4) When the 3-month expiration triggers, you have three options: Renew (information is still valid → set new expiration 3-6 months out), Update (information has changed → update the content and set new expiration), Archive (information is genuinely expired → remove from active system). (5) Track renewal rates: if you're renewing the same items every 3 months repeatedly, consider extending their default expiration to 6 months. If items frequently expire as genuinely stale at 3 months, your default is well-calibrated.