When I think of what electrical current is on an atomic level, i.e. electrons jumping/being passed from one atom to another, it makes me think of the idea that all the cells in our bodies are renewed from time to time, therefore we literally arent the same people we were 7 years ago ( I think it was 7 years). So, whenever I'm looking at an old piece of cable, it occurs that it may not be the same as it was when it was put in years ago.
With electrons moving, maybe that would explain why I encounter as an electrician, loose screws in electrical fittings so often. And it's a fact that we are not allowed to use junction boxes that utilise screws in places that are/will become inaccessable, under a wooden floor that is being tiled over for example, instead we must use accessories that have sprung fittings for the cables.