I expect the digital depth data overlay to give me a depth reading at any speed. At higher speeds, the graph itself may not have much to show me. I'm usually looking at a map with the digital depth data overlay when in Point A to Point B travel mode, so don't see the graph much. I would not expect it to pick up bait or other subtleties then. Below 10 mph, I want the graph to show structure and cover I can't see from my vantage point - to the hope that I can find fish there. I don't have to see an indication of fish to try a spot, but it is a nice bonus.