Bruce, thanks to your question I did some investigating. I had never really thought about it until I did. Seems 4 strand is good around structure like rocks. The 8 strand is better for casting.
Here's a utube video that did a good job explaining.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DGTK5EkBiKkQ&ved=2ahUKEwjT7ryWv8H_AhV_FlkFHTZ4CSsQjjh6BAgZEAI&usg=AOvVaw1gzJ3ne8dPvUw35eprWWrY