A collection audit sounds like a large project until you make the unit smaller. One shelf, one box or ten catalogue entries can reveal useful gaps without taking over the weekend.
Choose a clear boundary
Write which section you are checking and when you started. Compare the physical items with the catalogue entries. Mark missing records as unresolved rather than immediately assuming an item has been lost.
It may be in a current-listening pile, a different format section or with someone who borrowed it. Check those possibilities using your existing notes.
Fix only the fields that matter now
Prioritise identity, location and an obvious next action. You do not need to research every musician or transcribe every booklet while doing a location check.
Keep a short separate list of questions that require more time. This prevents one interesting edition from turning a simple inventory into an open-ended research session.
Close the section
Record what was checked and what remains unresolved. Return the items to their agreed places, then stop at the boundary you chose.
Use loan notes and location fields to reduce repeated uncertainty. A modest audit is successful when you can trust that small part of the catalogue more than you could an hour earlier.