How many years of college do you plan to pay for? 4? 5? 6? More?

Just did the math on this. . .7 kids, two already have BAs. We are paying for graduate program for one of them. 2 more in college with near full-rides, and 3 more yet to enter college. . . we will pay for about 24 years of college in all. Understood that each will finish BA/BS in 4 years. So far they have, or are on track to.