Yes, there are cases when documents may be delayed. We cannot give a 100% guarantee that they will be on a specific date, as there are many circumstances of force majeure (natural disasters, military operations, etc.) and legislation, according to which government authorities can delay them upon request in an additional inspection.
Reasons for which documents may be delayed:
1. presence of doubts of the ministry regarding the legality of the document (fake document)
2. presence of a criminal record, being wanted, suspected of committing a criminal offense, etc. (regarding obtaining a certificate of criminal record)
3. air alarms (ministries do not process documents during them)
4. technical problems with access to ministry registers
5. obtaining duplicate documents that were issued in the temporarily occupied territory
6. official holidays
7. military actions