The file is in somebody's inbox
The only copy of the signed annex sits in the mailbox of a colleague who is on leave. Technically it is not lost. In practice it is gone.
Three versions, one of them signed
"contract_final", "contract_final_2", "contract_signed". Which one holds is decided by the file date - which is to say, not decided.
The customer asks for a document
They call, someone searches, finds it and sends it by hand. Twenty minutes that repeat every day with a different customer.
Access is all or nothing
Either the folder is open to the whole department or to one person. There is no middle setting, so it is usually open.