I find this intresting an subject. I feel that since we are all of age, we know when the time is right for us as women. And any man with real respect for himself and for the woman he is with will respect this.
Only if they are in High School!
Peer pressure (only marry a virgin dude!)vs hormones (does she really put out?) causes many young men to be hypocritical.
However, if either party is just in it for the physical gratification, then "one and done" may certainly be the rally cry.
If I met a woman for the first time who indicated she wanted to be intimate, but wasn't going to, I would wonder why that was the case. For instance, is she being manipulative?
If I met a woman for the first time and she said, "I don't know if I do or not..." I would say she is being realistic, if not honest.
If I met a woman for the first time and she said "NO WAY!", I'd wonder how a blind woman could use a computer keyboard!