Been thinking about this for some time, and wanted to see what has worked best for those who have been consistently successful at getting into sexual relationships with girls through a series of "dates".
For the purpose of the discussion, lets exclude random encounters or one night stands, and focus on situations where you have asked proper (8/10+) girls out and took it to the end.
For example, I personally found that it usually takes on average around 1-3 dates/meeting/outings to get to make out with a girl and maybe another 1-3 dates to seal the deal.
Usually it would go similar to this: 1st Date: drinks/dinner at a bar (Brief make out); 2nd Date: Movies or other activity followed by drinks at the bar/club (longer make out session); 3rd Date: club/drinks at the bar followed by a movie at your place (closure).
Would be interesting to hear what has worked for others.
There is no algorithm really - every woman is different.
Personally, for me, I probably wouldn't go more than 5-6 dates without sex. That's if I REALLY like her.
Sex USUALLY happens on the 3-4 PROPER date mark, but can happen earlier (and occasionally later, if I'm really into her and we've come close to sex)