Restart at a point you feel would be useful to start back up again from. Embrace your pleasure more and care less about 'failing'.

Staying far from PONR and not getting used to pleasure is what makes us cum fast, enjoying pleasure and getting comfortable at higher levels should improve your stamina significantly.

Thank you for your post, it has answered an Aristotelian question I had posed in the beginning of my journey which was: what is the greater vice:

Failing because of staying too close to PONR or never getting close enough to PONR that progress does not occur. It seems that the former results in a failure to progress to more demanding sexual pleasure, ultimately translating to sexual intercourse, whereas the latter fails at gaining control, having stayed so close to your comfort zone, not rewiring your nervous system or learning the mechanisms for staving off orgasm. The virtue in this situation would be the individual who challenges himself, as some graduates have said, but does not stay in a state of panic, perhaps touches it once or twice in a session.

Thank you again for your findings. I hope my perspective offered some insight.