18yr olds have the same 24 hrs as everyone else. 
As I have mentioned elsewhere, I think the time has come to rework high schools and their overemphasis on AP courses. Let’s bring back vocational courses that are useful, like metal shop & home ec.
It is not the purview of the public high school to supply college credit. It is their job to graduate students who can contribute to society in an informed & thoughtful manner.