Not only do slow cookers save you time in the kitchen, but they can also save you money in the supermarket. A Glass Lid — A tight-fitting lid that holds in heat is essential to proper slow cooking. Heating Method — Standard slow cookers usually have a base that heats from the bottom and encloses a removable insert. Saves Electricity — Depending on energy costs in your area, slow cookers use less energy than your range or oven. Perfectly juicy, slow cooker chicken breasts require only two and one-half to three hours on LOW in most slow cookers.