spring - it's interesting how people refer to sex as moose burgers on here, given that it came from the concept of men wanting to hunt for a moose, and if you serve them up moose on a plate, they lose interest. Now it's become a catch all term for sex, no matter when it's had.
Personally, I think the longer you wait, the more likely it'll weed out chancers who are just after a shag, and also it will reduce the chance they'll suddenly lose interest because they've had what they wanted.
The more a man gets to know a woman, the more emotionally invested he becomes, the less likely he is to go cold afterwards.
Of course there is also the risk that he may be crap in bed, so there's a chance you may invest too much time yourself, only to find out it's unsatisfactory.
And of course there are lots of cases where people have sex when they first meet, and are still together years or decades later.
I've DTD with someone on the first date, and she was funny and witty and never returned my calls. And, not wanting to blow my own trumpet, I was far from unsatisfactory in bed. Other times I have been, but not that time. So it's not just men.
But I've found that when to bed with someone before, say, date 5, I'm less likely to want to see them afterward because... they suddenly become much less interesting and witty and fun to be with, and much more clingy and demanding. This is part reality, part perception, but.. that's what happens.