There are no clear rules in how long should sex last. The duration of sexual intercourse depends on the couple and many other factors. Example:
The circumstances. Young parents can't always afford prolonged sexual contact. Couples vacationing alone, can afford to stay in bed all day.
Preferences. Some couples prefer fast sex, while others prefer a slower pace.
Age and health status. When people get older, they sometimes need more time to get aroused and to reach orgasm.
The concept of "sex". Couples determine the sex. Some people perceive sex as the time spent in vaginal intercourse, while others - like the time spent in sexual activities (massage, petting, oral sex, etc.).
From a scientific point of view, the duration of sex is associated with a time interval intravaginal ejaculation. This measurement starts when the penis first enters the vagina and ends when the man ejaculation.
A study in 2005 of 500 heterosexual couples in five different countries showed that the average time interval waiting intravaginal ejaculation is 5.4 minutes.
It is interesting to note that the use of condoms and circumcision does not affect the duration of sex. Some men believe that condoms can influence the reduction of erection because reduce the sensitivity. However, research 2015 published in the journal of Sexual Medicine, showed that condom use did not affect the duration of sexual intercourse.
Pop culture inspired us an image of a real man, who can keep an erection all night. Formed thus the stereotype that steadily moved in our ideas about sex. And it became a problem, because many couples believe that their sex lasts is insufficient for long. Men worried in this situation the most, because I feel their impotency. The reality is that even if he did not have time to meet (and this task) your partner during intercourse, he can do it other ways.
How long sex should last, it is a unique experience for every couple. For some couples one minute is sufficient. Of course, "lover one minute" might upset a woman, but not every woman can bring to orgasm a simple introduction of the penis into the vagina.