There are many myths and exaggerated expectations when it comes to sexuality. That’s also true for the question of how long it takes men to reach orgasm during sex. That depends on many factors and can vary from time to time.
Measured on a stopwatch, it takes an average of 5 to 7 minutes for a man to reach orgasm and ejaculate. But the overall range is wide, from less than one minute to over half an hour.
There are also many differences in whether and how much a relatively early orgasm affects a man, his relationship and sexual satisfaction. In studies, men tend to overestimate the time it takes until ejaculation by a quarter to one half of the actual time. So it isn't a good idea to go by what others claim.
About 4% of men have almost no control over when they ejaculate. They then always (or nearly always) "come" very early – that is, before or directly after penetration. If these early orgasms become distressful, the problem is medically diagnosed as premature ejaculation. Various treatments are possible, sometimes including medication. Sex therapy is sometimes an option as well.