SI is a search tool. You can cover 500 total feet of water in one pass vs 20 feet. Once you find and MARK fish and structure with SI, and your map, then you go over that spot with DI. A closer look with DI will give you a better idea of the size of the fish and how they are positioned. Once you have done that then you switch to 2d sonar and fish vertical. This is the way I fish deeper water, say 10ft -80ft. If you fish shallower than ten feet then I would use SI, along with your map, to find and mark brush or rock piles. Once you have marked your spots then you just cast to those spot by using just your mapping and GPS.