When growth, geography, manager practice, and policy drift make a deeper rewrite necessary.
Policy and practice have separated
If managers approve flexibility, time off, expenses, or discipline differently from the written policy, employees receive two sets of rules. Resolve the operating decision before editing the prose.
Your footprint changed
New states, localities, worker types, leave programs, and working arrangements can change both legal requirements and the practical guidance employees need.
No one owns updates
Assign a named owner, legal-review trigger, version history, acknowledgment process, and regular review date. A handbook is a maintained system, not a completed document.