If there’s one thing men exaggerate almost as much as the length of their penis, it’s the length of an average tumble in the sack. But how long should sex really last?

People have come up with all sorts of names for penile-vaginal intercourse over the years – making the beast with two backs; knocking boots; laying pipe; dipping the wick; hiding the salami; Driving Miss Daisy – but if you’re a scientist, there’s only one thing to call it.

‘Intravaginal ejaculation latency time’.

Wink wink, say no more. Cue the wah-wah guitar pedal.

OK, so it might not sound sexy, but most studies into the duration of sex have focused on this. In layman’s terms, it’s the length of time between inserting the penis into the vagina and ejaculation.

How long should ‘intravaginal ejaculation latency time’ take, then?

This might sound straightforward, but it’s actually notoriously difficult to measure. You can’t just ask people how long they take – for one thing, they’re almost certainly going to lie, but even the most honest person in the world is unlikely to have any objective sense of how long they last.

But you can’t exactly put them in a room with a one-way mirror and watch them go at it, either – putting aside the ethical concerns, the act of observing is going to have a significant effect on the activity being observed, depending how shy or extroverted the subjects are.

The most reliable study into IELT duration, published in the Journal of Sexual Medicine in 2005, recruited 500 couples from around the world to use a stopwatch to time themselves having sex over a four-week period. It’s obviously not a perfect method – being ‘on the clock’ can be quite the mood-killer – but it’s what we’ve got.

The couples were pulled from a ‘normal’ general population, with no regard for any other conditions they might have, and the men were told to note their circumcision status and condom use.

So, how much wood does a woodchuck chuck?

There was a huge amount of variation in the average times for each couple, ranging from a brisk 33 seconds to a relatively tantric 44 minutes. The median time across all couples, though, was 5.4 minutes.

Somewhat surprisingly, the study found that condom use and circumcision didn’t seem to affect the couple’s times, challenging the conventional wisdom that penile sensitivity is connected to staying power. The study also found that the older the couple, the shorter the time between insertion and ejaculation, despite what any dirty old man might have told you over the years.

The study’s results are relatively consistent with a 2008 survey of sex therapists that found the majority of experts thought 3-7 minutes was an “adequate” IELT duration, and 7-13 minutes was “desirable”. Under 2 minutes was “too short”, but according to the sex gurus, 13-30 minutes was too much of a good thing.

… Is that it?

The problem with the stopwatch study, for our purposes, is that its scope is very limited. It begins and ends with penetration – and while that’s useful in researching premature ejaculation (which was the actual point of the study), there’s a whole universe of sexuality out there that it doesn’t even begin to touch on.

For starters, studies of penile-vaginal intercourse tend not to focus on the vaginal half of that equation. Sex is considered ‘finished’ at the point of penile ejaculation, with no regard as to whether or not the other party has climaxed. Sound familiar, ladies?

A 2004 study of more than 50,000 Americans in The Journal of Sex Research found that while 95 per cent of heterosexual men said they most often or always had an orgasm when they were sexually intimate, only 65 per cent of heterosexual women hit the Big O. (Interestingly, that figure skyrockets to 86 per cent for lesbian women, who also self-reported longer sex sessions than heterosexual couples or same-sex male couples in a 2014 study.)

In a 2015 survey of 1,055 American women published in the Journal of Sex and Marital Therapy, just 18 per cent reported that penetration, by itself, is enough to bring them to orgasm. So not only is penile-vaginal penetration a painfully heteronormative way to look at sex, but it’s not even how most people with a vagina are getting off.

Throw in anal sex, oral sex, mutual masturbation and group sex, and it’s clear that any study of how long sex is supposed to last is going to be far from definitive. Much like condoms, there is no ‘one size fits all’ solution.

Ultimately, what constitutes ‘sex’ is subjective, and what matters is that you and your partner (or partners) are satisfied.

If that’s not the case, you should raise your concerns with a doctor, a psychologist or a sexologist – but you can probably leave the stopwatch at home.