Obviously, it does not work for all colleges, because most do not meet full need anyways. But for starters you have about half the FAFSA EFC you would have had, if you have two students in college. That can drop you into a level of getting some additional aid at some schools. That can qualify a student for some state and college grants, work study, subsidized interest in part of Direct Loan.
It’s one of those things you have to request from each college as it is a PJ.