Well, it isn't really that hard even for nearby stars. You need to be sure to get an updated version of the library like once per decade. I think once you're further away than 100 or so light years the star movement is no longer apparent, and our galaxy goes up to 100,000 light years away or so, so most of the stars in the Milky Way are still far enough away that there's no apparent movement. These numbers are a bit of a guess and I could be off.