Knowledge is the new wealth. Reading 5 books a year is small.
I have already read 5 books this month. I have a goal of reading 48 books this year.
So even 20 a year is relatively small.
Although, it depends on the reader and how he/she can absorb knowledge in a short while.
I do not see any harm in reading 20 or more books a year. Of course that depends on the ability of the reader to read fast and understand the context, on the kind of literature of course and how challenging that piece of literature is for the person reading it, the time someone can spend reading, etc. Some people are very well able to read 2 or 3 books a week, some can hardly cope reading 1 or 2 books a year. And sadly some do not read at all or even have access to books for various reasons.
I think it is important to give the book time to digest. For some books I paced my self: only one or two chapters a day, because otherwise **I** can not retain and absorb the information. I read multiple books at a time though.
I think it helps read different stuff: practical, philosophical, fiction. If I try to finish a practical book in 1 sitting I know I won't remember anything in a month's time😅
So depends on your reading speed and time needed to understand the subjects.
Actually, it's not how far but how well. Some people claim to read numerous amounts of books for a short period of time without absorbing or understanding what the books are all about. If that is happening, then what is the essence of reading in the first place?
Some people are also able to expand their brain neurons making them assimilate and digest books very easily irrespective of the amount of books and this is because they were able to open a new pathway for their brains to engage in such act.
Some people may decide to read just 5 books in a year and believe me they can narrate the whole books for you from the beginning to the end. This is why I started with it's not how far but how well.
As for me, I suggest that we should not focus on the quantity of the books but let's focus on the quality of the books we read. It doesn't matter the amount of books we read in a year, but what matters most is how we digest, comprehend, understand and apply what we read.
Thanks for reading and I hope this helps.