Who it's for, and when
It's an athletic position, best kept for couples in good shape. Like any position, it depends on height, tiredness, creaky joints, and even the furniture. The lifted version, for its part, needs someone strong, with plenty of puff, to do the carrying.
It's most rewarding for partners of a similar height. Where there's a gap, heels and spread legs make up part of it. Beyond that, a lying-down position (missionary, or her astride him) irons out the height difference.
It's the position for urges that won't wait, fully dressed or nearly, anywhere in the flat. Just before the guests arrive, for instance, minding your clothes and your hair: most of the thrill lies in the situation. Not every time, but now and then, to spice things up.
Precautions: if you have back pain, fragile knees or hips, are pregnant or have limited mobility, ask a health professional for advice first. Pain during or after sex is worth mentioning to a doctor or a sex therapist. With a casual partner, a condom is still a must, even for a quickie. And if the urge strikes outdoors, stay out of sight: sex in public can be a criminal offence.