Hey James!
Just filling you in as I spotted your post. I think we both come from opposite sides of the spectrum and my habits may help you gain some insight about how to work on premature ejaculation.
I'm currently 25 years old, been masturbating since I was old enough to, maybe 13 or 14, somewhere then. I'm uncut.
I've always masturbated with an iron grip, dry and if possible, to porn. I didnt know it at the time, but my first 10 or so sexual partners I either faked it or straight up told them theyve got very little chance of making me climax and once they were satisfied we would stop. It took me a very long time to realise, I hated sex, thought something was wrong with me. Even if I pretended I could cum during sex, it didnt work. I'd literally go until I had no energy and the girl was completely raw, tried many different ways, it never helped, even without condoms (in an exclusive relationship, not for fuck buddies). I ended up asking my friends what the deal was, if they had the same problems...no one did.
Anyway, one day people are chatting on 4chan and I see a guy talking about having the exact same thing. I never post on there, largely go for the funny pics of cats and stuff, but here it was, some guy with the same issue. He said hed been masturbating with an iron grip and couldnt break out of the habit, sex was very unsatisfying.
He said the iron grip was the cause... I couldnt believe this is what it took for me to make the connection. Granted, it gave me a great rep with the girls, theyd always leave satisfied because without getting my fun, I was free to concentrate on making their experience the best I could.
The guy said he stopped masturbating for months. He never touched it once. Some sensitivity came back. Since then, hes been very gentle and he had been able to climax once or twice with a girl. He never used lube while masturbating, nor did I.
So, what we did to become SO desensitised that we ended up having epic (and unwanted) staying power? Iron grip, daily more than once, no lube.
I dont want this to read like im proud. I am not. It was horrible, still is. I've only ever had 1 girl work on it with me and in the end I still couldnt climax about 1/3rd of the time once we got to our peak of performance....that took 2 years.
So, if you overdo it and become desensitised, perhaps try what me and this anonymous stranger did, just stop playing with it for a while and eventually youll enjoy sex a bit more again. I never had premature ejaculation, but the iron grip sure affected my staying power, so I would say it supports your idea to some extent, as once I eased off, I did get more sensation and quicker ejaculation times.
That being said, the target of being so desensitised where you have to pull out and finish yourself off....I wouldnt go with that as a target. I've been that guy. Girls dont expect it,
they dont like the sight of the guy they were having sex with mere moments ago in a grimace of self-abuse, raking his penis with a claw in a vice grip like a pit bull gripping on a chew toy. Dont pretend it's normal, I even tried putting a game face on....it made me look more psychotic than casual about the whole affair
Just go for a point where you have to really pump away for a long time in order to climax, I've managed to more or less get to that point and I never climax without the conscious decision to go ahead and I still last as long as I want with girls, in fact, the first few times with any girl I usually just dont, simply because my mind has to be in the right place with them before I can. Maybe adjust your goal, but thats my personal experience talking and I dont want you to feel like I'm calling you out or anything, everyone has their own preference, goals and ideals...but I'm in a situation which youre aiming for and I dont particularly like it.
EDIT: This all being said, nowadays, I'm looking at penis enlargement. My vice grip over the years (and currently) has never given me great erection quality for a significant time afterwards, so I have to be sure to not masturbate for some time before any chance I might get lucky. The vice grip hampers my recovery between workouts, potentially moreso than people who masturbate with a medium or light grip and I cant ejaculate without it now, so as youll see in my log, I just try to refrain from masturbation whatsoever, which is difficult when you have it as a lifetime habit to masturbate when you get up, when you get in and when you go to bed.