This is such a great question, and not an easy one to answer. Given so many “good books” have been written, we are all aware that it’s impossible to read them all. Thus, we are often admonished to focus on the “great books,” the BEST of what has been written or said. But even then, we are in over our heads. For me, I don’t have set plan for new vs. old but I do focus on those older books that inform the newer writers, and then try to only read those newer authors who are saying something important about the application of wisdom to the modern condition, not just regurgitating what has already been said by the older authors. A good example of such a newer book is Rescuing Socrates by Roosevelt Montas. Something else I read recently to this point really resonated with me. I’m paraphrasing here: “We are better off building a library of books we want to read and then constantly be reading ‘in our books,’ communing with these authors and not anxiously trying to get through all of them.” I’m not sure if that helps but your question is sure one that resonates with many of us.