Read the "Cast Net 101" thread in the "Live Bait Equipment" section. My opinion on this matter has not changed one bit.
I will tell you that this time of year when the water is still around 50, it is real tough pulling up bait from 30 feet during the day. The big gizzards are still very fast. It is easier to get em at night when they don't see the net coming as easily. Once the WT reaches 45 or so, the big gizzards become very slow and are easy to catch at any depth. You just need the right net.