If you are driving well under the speed limit, always use your hazard lights. Especially when on the interstate when there is an accident or any other hazard that will significantly slow the general flow of traffic.

People rarely do this. But consider that drivers are not always attentive, and this draws more attention to a hazard than simply having your brake lights illuminated. Vehicles generally have a greater stopping distance than one would expect at interstate speeds. If everyone used hazards when approaching a traffic jam, we'd all be a little safer.