This new york times article talks about how highschool students who are far behind can finish-- if you just give them more time.
I believe strongly in eliminating expectations on time. Why should you get a HS diploma at 18, college diploma at 22, married at 23, promoted at 25....etc?
This precludes all interesting paths, like traveling the world for a year, earning money needed for family emergencies, spending time doing real community service, or playing in a rock band before you get your PhD in your late 30s (I know someone who did this).
Forget the timeline, people.