It depends how far you want to go.
Do you want to go this far? Do you need to go this far?
According to Wikipedia the latest release of the LTS book was 1st September 2020. I would not use a book about Linux if it was 20 years old.
There used to be a saying, something like, "If you uses...
To some extent it depends on what you are using it for and how much data you are carrying.
Being a Database Administrator is not a light thing. For some people it is a degree subject.
There is a danger in making a fairly serious mistake so backups are very important.