After I've posted a list of my favorite songs of the year, I have to accept that some great songs might have escaped my attention. There are always at least a few in any given year. Six months from now, I might read or hear a review that casually mentions an artist's "best recording, released last year."
At first, I'll think, "Arrrrrrggggghhhhh...How did I not hear about this before now?"
Then, I'll make peace with the fact that, try as I might, there isn't time to hear every piece of recorded music that was released in a year.