@rwsmith

I agree, had to think on it a bit. I feel the phrase does originate with the concept of homing in a target, but I like the nuance of hone as sharpening a focus or fine tuning something. Even an archer adjusting his aim to get closer to his target on successive shots could be said to be "honing in" on it. In any particular situation each phrase is probably somewhat more appropriate than the other. Thank goodness for language evolution, otherwise we'd all be speaking Proto-Indo-European or something and life would be boring.