How much time and effort may have been put in?

[Koen G]

TL;DR Hobbies dont leave much evidence.

Which means that we can only speculate. And perhaps a literary hobby might have slightly better odds of leaving evidence? I struggle to think of instances where someone made a book that wasn't either for profit (i.e. professionally), for practical reasons or for religious reasons. 

Regarding the early modern period: what innovation has had a greater impact on European literary culture than the printing press? We can't just take early modern literary practices and assume that those would also have existed before.