If you train your whole body, lifting weights via a dvd or your own free weights plan, and you don't feel doms or any muscle tightness/fatigue the next day, then you are good to go. I don't care what the literature suggests on this. I'm not saying anyone should be lifting the next day, but if I don't feel a concurrent result the following 24-48 hours (and you should know the different ways the body responds to lifting) I wasn't putting too much into the program. So there really isn't that much to repair. Your question though, is more complicated if you are a beginner, and then it goes from there such as: your age, average nightly sleep, diet, stress and nutrient timing.