Even the CPR class I had to take touched on this. You're unlikely to do much other than break some ribs on an adult, which is not going to be fatal. You just do CPR because what else are you going to do. The same class also did cover that AEDs are basically everywhere and pretty much anyone can use them as long as you remain calm. It also covered that mouth-to-mouth CPR on a 7 year old is a good idea because they tend to do weird stuff like choke on some toy or their food. 47 year olds rarely pass out from choking on food.