At a given configuration, the only thing that matter to achieve the longest gliding distance is the AOA. The best gliding distance is obtained at L/Dmax. Beside following the GS is useless as it leads far beyond the threshold, this leads to increase the AOA, building up drag thus highly reducing L/D and gliding distance. Energy is a factor of force by distance. The more you spoil in drag trying to follow the glide, the less distance you can fly. Once no more kinetic energy is available (stick shaker), the only one available is the potential energy, which is also based on distance... but only the vertical one. The potential energy will anyway be used till the plane reaches the ground, what matters is to improve the L/D in order to spread the use of the kinetic energy. The drag reduction between 25 to 30 is probably meaningless compared to the generated drag at a 16 degrees nose up attitude.
