Basically everything is possible and nothing can be predicted at all.
it is a bit logical that it can not be predicted, and how it could?
I mean it gives a "marketing" advantage to the girl, it is that the girl is suddenly and immediately known by everybody in the business.
If you are booker, and that after fashion weeks you have 2 new faces, one who has booked 5 B level shows, and one has been Prada exclusive, if you send their pics to a client, obviously the client will probably already know the Prada girl and has never heard the name of the the other one, so it gives a little advantage to the Prada girl, it is obvious, and that's why for agencies, exclusive are still a very good thing to get.
But that advantage is just at that first step, at the end if the girl is just not the type needed for most of other clients, Prada girl or not, it will no help her to book stuff.
Also the timing is damned important, as the little hype it brings is really short, so in case it works, if the girl is back to school and not able to accept booking before the season after, she destroys her chance by herself, and it happens like that more often than people seems to think...