In all honesty, you should fish with whatever gear ratio your comfortable with. That being said, as far as my understanding is concerned, you want a 6:4:1 gear ratio for square bill crankbaits, because you want the extra speed to burn them back to the boat. Conversely so, you want a slower, 5:3:1 gear ratio for deep cranking, because your want more torque and power, opposed to speed. If your like me, and don't have unlimited money to buy three different cranking setups. I would recommend going with the 5:3:1 gear ratio. It will work good for all your square bills, and great for all your deep divers. I hope this helps,
Cam