in
most cases there is no need for separate Libraries if the Library structure is default (or has the same custom columns)
Those groupings are the traditional Use of Tags. You can assign 1 or more tags to any book
You the can use the Tag browser to select which Tags, Authors, Series... to show. You can also save a search and/or make that into a Virtual Library (VL) and view that.
There is no 'Overnight'. A view changes in seconds
Great Reasons FOR keeping separate Libraries
Parental Guidance required subjects

Shared Public Domain isolated from not public shareable
Library custom Column differences (usage)