It would be beneficial if there was a way to pull a report of the Hierarchy to audit the database as to what fields are being used and by a count. Example would be to see how many of the files are using a particular classification and which are not to produce a report all at once rather than one item at a time.
You can run reports in Cloud Explorer in filter on Discipline and Classification. The search results shows the number of found documents. You can also export the report into a spreadsheet for further analysis.