I'm working on 100 yards apart per hive:
Yikes Eddie! You're more of a man than me! I suddenly feel like a slacker...
EDIT: to answer the OP's question, I am a firm believer in eyeballing it and going with it. I've thought about going to a small circular configuration, with all the entrances facing out. That should help equalize the drifting, but I have yet to do it.