Edging is great for prolonging the pre-orgasmic moment, if that's what the OP means. If he means prolonging the act of ejaculation itself, edging can also help by increasing the build-up of seminal fluid, and the overall tension in the ejaculatory muscles. You can get some great long-distance shots that way.
For many men the duration of the ejaculation can relate to the amount of seminal fluid build-up prior to orgasm (though not always). Basically it means you tend to keep cumming until you're empty, and if you're full, you'll go longer. And personally, I feel a big load as being more intense, and therefore more pleasurable, than pumping out just a few drops when I'm doing repeats.
The prostate and other glands that contribute to the total ejaculate will start to produce more fluid during periods of foreplay & arousal. Longer foreplay will result in greater fluid. So will periods of abstinence, though some men will automatically expel any excess in the nocturnal emission known as a wet dream.
Therefore, for the longest orgasm experience, most men should:
- engage in extended foreplay immediately prior to sex
- abstain from sex for 24 hours prior
- brink/edge a few times during foreplay
- stay well hydrated
- avoid alcohol, cigarettes (depressants & vaso-constrictors) and most drugs
- have sex during periods of higher testosterone levels. For most, this is actually first thing in the morning, not at night just before retiring.
- be physically rested
- introduce exciting novelties to the usual sexual routine, for a psychological boost
There is a point of diminishing returns for some men, however, after which prolonged foreplay will begin to tire them, and to dull & diminish their senses, rather than heighten them. Each man needs to know this point, and go on to their climax when they approach their limit.