I know somone who just “knew” on the second date that if he went through the shadchan the girl would say no to a third date. He also had a strong feeling she would be too embarrassed to say no if he asked her directly. So before the second date ended he asked her for a third date.
She was too embarrassed to say no, so they had that third date. Not only did they get married, but they are still married long enough that they are grandparents.
And later on he found out he was right about something else – she would have said no to a third date if he had gone through the shadchan.