[PBRSTREETGANG]

...thus if the timing is right they move the sperm of men who are more "skilled" closer to the egg giving them an advantage over less "desirable" men.

That ideal "timing" requires the man to ejaculate before the woman achieves orgasm and then to continue until she does shortly thereafter.

That's a tight window to work in...so to speak.

[discostu]

Some women tend to "trigger" when the man does his business if he's gotten her close.

Of course when you sit down and consider all the thing that have to go right to bring a child into the world, it's all a pretty tight window to work in. The thermo-dynamic miracle of life as Alan Moore called it.