Honestly, I don't play with zone rules that much. It's an attempt at bridging the gap between theater of the mind and somethin more mechanical and I don't think it works in most cases. Basically it boils down to range for movement and range for attacking. Like a river could be a separate zone from the other sides to represent the difficulty for getting to the other side, but somehow it also counts as long for weapon rage which affects the verisimilitude.

I've used it in Conan and Soulbound but honestly I think it was intended to be handwaved away, which IMO makes a bad rule.