You don't have to troll to catch walleye. Regardless of if you are drifting or trolling you are going to catch junk fish. Listen to what the fish are telling you. If you are drifting and casting using a count down or something and every time you do that specific technique you catch a sheep head, change it up. Fish higher or lower or change your weight change the speed, move to a new spot or whatever until you catch a walleye and then try to reproduce that technique. We limited out Sunday. We caught 7 drifting, and then switched to trolling after the wind died and caught our last 5. We tried trolling higher in the water at first and where just hammering huge sheep head. We lowered our presentation and started catching mostly walleye. When we were drifting it was the opposite. If we ran our baits low we couldn't keep the sheep head off. Had to fish high to catch the walleyes. If you are catching only junk fish, change up your presentation.