I agree with most of what WTP wrote.
I would also add that I think that nowadays (shidduch crisis or not), it makes sense for many girls (who are looking for learning boys) to wait a bit before starting shidduchim.
Since the “ol parnassah” will fall on the girls, many of them need some time to either go to college or get training in some kind of career. Even if a girl is not going to go to college (whether for hashkafic or other reasons), she may need time to figure out what she is going to do, and to get some training and/or start working in her field.
“Waiting a bit” can mean a year or two after seminary. That means they will be approximately 20 when they get married. That is not so old, and that year can be crucial. Some girls finish their BA and/or MA in that year, and others have a chance to figure out what they want to do and to start working.
In Eretz Yisrael, the girls go to school for two years after high school. During those two years, they have a “major”, receive some type of certification, and obtain a means of parnassah. Most of the girls do not start shidduchim before Pesach of the second year. (I know that we have argued about that in the past, WTP, but I have a friend with 10 daughters who were, are, or will be in the Yashan, and that is what they told me, and the Yashan is the largest and most classic BY in EY).