Optimistic Concurrency only locks records from the time when the actual update is performed.
Following are the advantages of using OCC:
Records remain available for other processes to update if they have been selected from the database but haven't yet been updated.
Records are locked for a shorter length of time.
Fewer resources are used to hold the locks during the update process.
Reference:
https://docs.microsoft.com/en-us/dynamicsax-2012/developer/optimistic-concurrency-control