We’ve all watched movies where the six hundred bad guys line up neatly and each fights the good guy one at a time, allowing himself to be defeated. Unfortunately some fight scenes in novels are written a bit like that too. There are three or four bad guys but we read about the good guy, punching/hitting/shooting Bad Guy #1, then Bad Guy #2 and so on. Real fighting is not like that. The bad guys want to win so they get paid, and they’ll all attack at once, whenever the good guy is off guard, has his back turned, or is busy fighting already.
Choreography is important in sex scenes too. Sometimes the hero has his hand around the heroine’s waist, gently lifts her chin up to kiss her mouth, and simultaneously undoes her hair from its ponytail. Unless he’s an octopus shapeshifter, he’ll find doing all that at once tricky.
It’s even harder with a ménage scene. Count the number of arms, legs, hands, mouths. Then check to see whether the bodies really can be positioned like that. I know of a popular erotic romance author who has broken the arms and legs off several Barbie dolls while choreographing her love scenes. It’s important to get the choreography right.