5/8" is about average for me, although there are a few bows I have that were tillered for 3 under that could go 1/2" or even 3/8". Frankly, I'm inclined to set them all on 5/8", since that seems to give me a more consistent POI among different bows.
I have found that as my form and release improves, my nock point has gone down. A few years ago I would have said my average was 3/4."