Do not sample unless there is no other way to deal logically with a volume of records. The following explanations should help to understand what information is actually needed. Be precise when obtaining and recording the data. Location, Physical Custody, and Legal Custody. These are interrelated, but different.
Location indicates the exact placement of a record at the time the inventory is taken.
It is essential that locations are recorded exactly, since you will need to be able to find each record again after the inventory has been completed. While this may be so, it tells you little that was previously unknown. Physical custody indicates the office and official in possession of the record at the time of the survey. If you find a record in the recorder's office, the record is in the physical custody of the recorder. This information is essential for establishing paper trails.