This is from personal anecdote and from what I have read many others report on this site and 'yourbrainrebalanced'..
In conjunction with addiction related brain changes I believe for some us PE is also a muscle related conditioning dysfunction. I believe the pelvic floor plays a huge role in PE, even for some porn addicts. For many years, many of us watching porn were probably unintentionally clenching our pelvic floors because it felt better and it would shorten the time to orgasm. Over the years this conditions our muscles of the pelvic floor to behave in a certain way, to become rigid and tense until it becomes more permanent even when unintentionally clenching, just like postural habits. "Practice makes permanent" if you are constantly checking your posture and correcting it, it will eventually become your natural posture without having to think about it. All muscles, including the ones controlling your penis are able to be changed in the same way
To know if you pelvic floor dysfunction and what to do about it you could either go to a urologist or try and diagnose yourself: https://www.pegym.com/forums/premature-ejaculation-forum/49636-pelvic-floor-balance.html (This site may contain triggers)
Ofcourse, rebooting and rewiring can only help but sometimes not all of the conditioning is purely reward circuit related
