It's the use case that decides the use of Shallow clone or DEEP Clone
Data is physically copied to the clone table in the case of a Deep clone. A deep clone is very useful to copy the data and have a backup of the data in another region/env. The typical use case is Back up and disaster recovery.
In the case of the Shallow clone, only the metadata reference is copied. This is more like a view pointing to the data at a point in time.