I have read a few places where there is an actual genetic link to time before ejaculation. This thought offers little hope of drastic improvements. Some here on this thread seem to be agreeing with this. But these scientific suggestions were saying things like "a 2 minute man might vary from .5 to 5 minutes, but not expect go get to 20 with any amount of training or effort." At my age, I'd be to tired at 20 anyway.
There are also evidences that suggest social factors as well. Some call it the beta male effect. It is tied to the male's confidence and social standing compared to other males in his social groups. When and if the beta male gets to mate, he has to get it done quick if he expects to spread his genes. This is an innate response that we as higher socialized beings probably aren't conscious of. I don't buy into all the evolutionary who ha but I do think confidence can play a role in this for some.
Certainly frequency can play a role. I have noticed the more often, the longer I "tends" to last. But that is a loose tendency. Overall arousal plays more into it for me more often than not. But then sometimes, it just seems to go on and on and I have to work to get there. Other times it's a few seconds of glory only. One thing I have noticed is worrying about it does nothing but make it worse. Worrying about staying hard long enough to please the wife does little good either.
I've not been masturbating with any kind of regularity for several years now and I see no difference in the effect. Intercourse is just a whole different field of play. There was a time when I may have MB 10-15 times in a week and I saw much the same results as I have just shared in intercourse - varied. Though I would say that maybe overall - say 3 times out of ten - I would last longer back in the MB days. So physically, perhaps there was a "benefit" for me occasionally. But the mental price, the emotional price MB cost me was far greater then any perceived physical benefit. I'm never going back there. Intercouse is sooo much better now in sooo many ways.