i have been using this technique, the stress relaxation factor and would attribute that to my increase in flaccid length.
I used to always have me penis in a constant Kegel, which i believe always led me to be in a retracted state. Since focussing on the relax factor, i have improved my flaccid to a constant 4-4.5 inches even when held up in tight briefs.
I use this method when i am hanging and can honestly feel a greater pull when i fully relax, it makes sense, however it takes practice.
When applied to the art of PE, I believe it to bea great asset in not only making gains, but cementing them through the constant tension theory.