I've decided not to care too much as I don't buy a lot these days.
As I've said in the Vent and Rant Thread in the Lounge, I've never read anything by Agatha Christie; not a single story featuring Hercule Poirot, even though I love to read Sherlock Holmes.
Therefore I've bought the Complete Short Stories of Hercule Poirot, and every book featuring him, and I went all around the globe to get the best prices and coupons.
I bought most of my 900+ books between 2011 and 2014, and my purchases since then were limited. I just add to my library what interests me at the moment (which is mostly stuff I've heard of for a long time, but didn't get around to reading), and as I will probably keep this library the rest of my life (in EPUB or a future format I'll convert it to), I don't worry too much when I'll read what.