So it is like an audition for a relationship? ... the idea that one can immediately recognise who they find attractive in the medium to long term is patently false anyways...
Yes, it's like an audition for a relationship. But you do not immediately need to recognize anything long-term: it's an audition for the *sexual* part of the relationship, which you seem to be placing no importance on at all. Some of the longest-running relationships *I* know of started with sex and then turned into something else later. As I said before, I'm sure the mix is roughly proportional to the general sexual habits of the single populace, and we are just picking out the examples we like.
How is a night spent getting to know someone new "wasted"? Getting to know someone, even if they turn out not to be the kind of person you want a relationship with, is a worthwhile experience -- you might learn something new, get a new perspective on an old situation, or simply recognize that their personality is less compatible with yours and more compatible with that of one of your friends; then you could introduce the two. Again, examples of friends ending up in relationships with people their friends pulled just once abound. And how is a night spent not interacting with your friends "wasted"? Sometimes I spend the night not interacting with my friends just because I *don't feel like it*, and I don't consider that wasted time. Running jokes and anecdotes are a dime a dozen, generated every time a group of friends gets together. They're nice, but they're not exactly rare and valuable, while good men remain proverbially hard to find.
I see my friends all the time; I find a guy I seriously want to go after much less often. Of course I'll go for the guy. But if I'm not hoping to get a second date out of it, then as Mikey said, it's just remote control masturbation. Sleeping with someone who seems nice, only to discover they're a psycho is just as pointless as spending a week going out "for coffee" with someone only to discover they are intellectually bankrupt. That's essentially my developing thesis here -- it's pointless, yes, but no more or less pointless than the other approach.