You get much greater strength development in the 1 x 20 RM strength training program than in any of the common high intensity strength training programs presently used by athletes. The reason for this lies in intensity and adaptation.
The 1 x 20 strength training program has less intensity which is better suited for adaptation. In other words, the body develops strength at a faster rate, i.e. adapts to the strength training program faster than a high-intensity program. As a result, over a few weeks you will have greater strength than you do on a high-intensity program.
In addition, because of the multitude of exercises used in the 1 x 20 strength training program, you develop more strength in all the major joints rather than only some depending upon the exercises used in the high-intensity program. This is another factor that plays a role in the prevention of injury for which this program is known.
For more information see The Revolutionary 1 x 20 RM Strength Training Program.