If I catch two or three fish, I try to find out where the fish are positioned and at what angle they seem to be hitting best. Then I'll position the boat the best way and use the trolling motor or drop anchor. Even without a depth finder, anglers can eliminate considerable fishless water by using a sharp eye. Where canals intersect other water bodies makes an excellent starting point. Look for anything different or out of the ordinary such as a washout or sudden depth change.
Fish frequently hang just over the edge of dropoffs.
Check points, cuts, pockets, and any place where water flows from one body of water into another. Fish often lurk at the mouths of such cuts. To prevent this, many anglers only fish pipelines at odd times or during the week when fewer boaters travel through an area. Typically, anglers venture from marinas at first light or within an hour of daylight. If I'm not the first one out of the ramp, I'll usually start on the lakes and other points.