The paper addresses the extraction and empirical testing of the hard core of assumptions underlying the construction principles of the German supportive system in youth elite sport. The support system turns out to be based on a mainly input-oriented concept. Invested sport-related time is regarded as a critical input variable and extensive and intensive time economy is systematically aimed at. Among 1,558 national squad athletes in all Olympic sports, those with international and with national success at each junior age and elite age are compared regarding their former juvenile success and volume of training and participation in support programmes. Effects of juvenile training- and support-related variables vary over time and in some cases turn into the opposite in the long run. Juvenile success, the training volume in the individual’s current main sport, and the inclusion in support programmes have no significant or negative effects on long-term success in elite sport. In contrast, international elite athletes are characterized by a higher juvenile training volume only in other disciplines beyond the individual’s current main sport and correspondingly by a decelerated juvenile training-, competition-, and support-related development in their main sport. Results are discussed by integrating social science, training science, economic, and educational perspectives.