I have to mention that doing multiple stretches “should” have an effect called hysteresis. This means that breaking up 15 minutes of stretching into multiple reps should produce more of an increase in bpfsl than holding a stretch for 15 minutes straight. It is my own belief that this explains why jelqing and manual stretches are effective, even though total time under tension is less than with extenders or hanging.
This hysteresis effect (penis not returning to the initial state after stretching) is arguably real for durations of a few minutes. It is responsible for getting progressively larger BPFSL measurements when repeatedly measuring for some minutes. If the workout is resumed after an interruption of more than a few minutes, the BPFSL values tend to fall back to the initial measurements.
When I opted for many repetitions of 10 seconds maximum extension stretches versus long duration stretches, I was thinking less about the hysteresis effect, but more about the need for oxygenation of the tissues. An even more stringent practical aspect is the discomfort of holding the BPFSL stretch for longer durations. The 10 seconds hold was a good compromise.
Starting BPEL: 6.9" (Dec.1st, 2008)
Current BPEL: 8.11" NBPEL: 7.63" BPFSL: 9.09"
Current MEG : 5.6"