I agree about the emotional connection (at least for making better sex). For some it's emotional, for some it's just a release, even in a marriage. ~But~ I'd venture to say that a very high percentage of adult relationships result in sex within a month, probably a bit less. Not many people waiting 6 months, 1 year. I think you'd agree with that.
How much of an emotional connection do you have in a month? In 2 months? In 3? A bit more than a first date of course, but honestly I doubt you have a significant emotional attachment at that point. If so, I'd question your personality as being a bit dependent and would say you're in for a lot of devastating, emotional breakups at the 3-4 month mark when people see the everyday person, the good and the bad, not just the good, and tend to become bored or disinterested.
I think it's just the perception that you know the person better at that point, perhaps trust them more, so if you have sex, there's a better chance for the LTR. I just don't think that's the case. It's a roll of the dice.