That depends on
a) your threat model, and
b) the physical security that applies to the book in question.
Even for one given user, it is not the case that one-size-fits-all or, conversely, it is the case of “horses for courses”. The security that you apply for your Purism forum password may differ from the security that you apply for your internet banking password. You would enable 2FA for internet banking (where it is a viable option) but you may think it unnecessary for the Purism forum login process.
For every user, you would also plan for backup - since you don’t want to lose all your secrets. (In that respect, a book is a bit crap because it is difficult to keep a backup up to date and tedious to make the backup.)
Still, if @tracy wants to use a book (he didn’t say that he does, this is just an example) then that is better than only reusing a few easily guessable passwords across the entire internet and probably better than writing a bunch of strong passwords in a plaintext document on the target computer.
Each user should do something but each user should only go as far as is realistic for that user.