Test each hierarchy level by removal — if promoting…

For each intermediate level in a hierarchy, test whether removing it and promoting its children one level up would lose meaningful organization—if not, flatten it, because unnecessary levels are pure navigational tax.

When This Fires

During hierarchy audits or folder restructuring
When navigation feels cumbersome despite logical organization
When intermediate levels contain only 1-3 children (too few to justify a level)
During any simplification effort on an existing classification system

Common Failure Mode

Keeping levels because they feel "tidy": "It's more organized with the extra level." Tidiness is not the criterion — navigational value is. A level that looks tidy but doesn't aid retrieval is decorative bureaucracy.

The Protocol

For each intermediate level in your hierarchy: (1) Mentally remove it and promote its children to the parent. (2) Ask: would the parent become unmanageably large (>15-20 items) or confusingly diverse (items with nothing in common)? (3) If yes → keep the level. (4) If no → flatten. Remove the level, promote children. The navigation tax disappears and no meaningful organization is lost.