ADEP really does not set the hyperfocal focus at all. And the shutter speed really has nothing to do with this, at least directly. What ADEP does is what you wrote but again I would not use the term HyperFocal. One can find that on most lenses (especially older SLR lenses) one sees a hyperfocal scale on the lens barrel, and allows the photographer to set the fattest DOF between where he stands and infinity for a given f-stop.
Hyperfocal focus is the optimum focus that will give you the fattest DOF for a given aperture and focal length used from where you're standing to infinity. This is not what ADEP does. ADEP optimizes the DOF between two points for a given f-stop...clearly different.
As to the good of this feature (ADEP), I really think it sucks because when you define the two points, the two focal planes are skewed by the arc movement of the photographer. This causes erroneous results when ADEP is calculated by the camera. The wider the aperture the worse this error becomes. This type of focus error also happens when one relies solely on the center focus point, uses a fast aperture, is fairly close to the subject, and then recomposes...bad camera workflow, to be sure.
ADEP is a stupid gimmick!
Better to learn your lenses and how the f-stop effects DOF for a given distance from the subject/s. The DOF Preview button can often help in this endeavor.