Delete singleton tags, keep tags connecting 5+ notes across 3+ months
When a tag appears on only one note, delete it during review; when a tag connects five notes from three different months, preserve it as earning its maintenance cost.
Why This Is a Rule
Tags have maintenance costs: they occupy cognitive space when browsing tag lists, they create noise in auto-complete suggestions, and they split attention across tag-selection decisions. A tag earns its maintenance cost only when it connects multiple notes in ways that aid retrieval. A tag on one note is a label, not a connection — it adds overhead without providing any retrieval benefit you wouldn't get from the note's content.
The two thresholds form a retention filter. Delete threshold: a tag appearing on only one note has zero connective value. During review, delete it. If the concept deserves a tag, it will re-emerge organically when another note warrants the same label. Preserve threshold: a tag connecting five notes from three different months has proven its retrieval value — it's surfacing a genuine cross-temporal pattern that would be invisible without the tag. This tag has earned its place.
Between these thresholds (2-4 notes, or recent notes only), the tag is in probation — keep it and check again next review cycle.
When This Fires
- During periodic tag hygiene reviews (monthly or quarterly)
- When your tag list has grown unwieldy and auto-complete is noisy
- After migrating notes from one system to another (many orphan tags appear)
- Any time you notice tags that seem pointless but you're unsure whether to delete
Common Failure Mode
Keeping every tag "just in case." Tag lists grow to hundreds of entries, auto-complete becomes useless, and the cognitive overhead of choosing tags during capture slows you down. The singleton tags are the worst offenders — they take up space and connect nothing. Pruning them is cost-free because a tag on one note is functionally equivalent to no tag.
The Protocol
During tag review: (1) Sort tags by note count. (2) Delete all tags appearing on exactly one note. (3) For tags appearing on 2-4 notes: check if notes span at least two months. If yes, keep. If all notes are from the same week, the tag may be a passing interest — keep on probation. (4) Tags with 5+ notes from 3+ months are proven connectors — preserve and consider promoting to your core tag vocabulary. (5) Repeat quarterly.