I keep my finder on the 200hz setting and mainly am looking for big bait balls and monitoring the bottom depth. I don't really bother with the split screen/dual frequency. I'm not sure you're really getting any additional info that's worthwhile doing that. I think you're better off spending your time checking your rigs and making sure they are working properly.

When I find a good bait ball, I run one rig above and one rig below and try to stay with the bait by circling around it a couiple of times. When bait is scarce, keeping the rigs in contact or near the bottom is what I do.