We don't know what man spread the rumor that duration has anything to do with the quality of sex, but we do know we want to punch that dude in his overactive dick. Most nights, these marathon sessions just have us silently begging for mercy for our uteri and agonizing over how much sleep we're losing. Save the into-the-wee-hours sex sessions for vacations, when you have nothing to do but bone the day away. On a daily basis, 15-20 minutes (not including foreplay) will do just fine.

Even spontaneous quickies are appreciated over an hour of mindless, machine-like thrusting. As long as your sex life isn't subsisting on quickies alone, you'll never be faulted for the occasional wham-bam-thank-you-mam.