I would add to this thread that gauging pressure by your length in the cylinder, is not reliable at all. I can easily be 1/2” longer at the end of a session if I enter the pump erect and remain erect, compared to pumping at lower erection levels.
The pressure also feels different if you are very erect in the tube.
Further, if you are fatigued, BPFSL tends to shrink and this may lead to shorter length in the tube. If you judge pressure by length, you will then amp up pressure even further to reach your checkpoint length, wind up at high pressures and wound up even more fatigued.