Honestly, that is the one thing about YNAB I do not like and that doesn't work for us.
We have spent about $4,000 in the last 10 years on car repair, and that includes new tires for all of the cars.
We have to save for college. We have NO idea how much it will actually be. The private school one son may be looking at is $40,000 per year. The trade/tech school another child is looking at we could write a check for tomorrow. However, we have NO CLUE how much it will really cost. Home repairs? Well, we have no clue as things come up (like a leak in our fridge that ruined our kitchen floor) as to how much will really be needed at any given time.
A general fund is much more workable for us. We don't go "blow it" on things we want. All of our emergency fund and savings is for things that we need.
We have no debt other than mortgage and we have a healthy savings account (general savings, no "you have a specific job and can only do that job" stuff), and retirement.
I see no reason to change the way we are doing things.