In the real world you'd have to try pretty hard to find 12 inches of uninterrupted muscle to shoot through. So it is a little limited. But people want, so very badly, for somebody just to tell them what's best . And that desire has led to the downside of this work. People who did not study the data, or recognize the significance of it, madly rushed once more for a hardware solution to a software problem.
Nothing can replace learning how to shoot.
This should not be construed as critical of the FBI methodology. It is not. In fact, the things we learned as a result have really turned the engineering of handgun ammunition on its ear. Today there is very little difference among the major maker's high end defensive ammo. Because they all use the same method to test new designs.