Just to throw in a slightly contrarian position:
The research on fluid intelligence and working memory consistently finds that they both peak at about age 23. So if individuals postpone college until age 25, undergraduates will be in school during the downslope of their natural capacity to absorb novel ideas and skills, and those who go on to postgraduate study will be attempting to make abstract and creative connections after the major drop-off in fluid reasoning and working memory that occurs at around age 30.
I think we should consider stronger baseline scaffolding across the board for executive functioning during college, and lower the average age of entry for those who are truly 4-year college-oriented, especially if they are moving toward fields that require post-graduate study.
NB: I might have an argument for the reverse in the back of my mind, too.
