This basic question really isn’t about the kid so alert and organized, and with parental help, that it’s defensible. Nor just the multi school UC app.
It’s about kids who really aren’t able to be on top of all. And who think casting a wide net means more admits. @sdscoutmom, I might call your list “6 schools plus in state publics.”
Many kids have trouble knowing how to make the best of their apps. They need a couple of reasonable safeties, a few matches, then decide on maybe a reach or two. 20+ is dreaming, making this a crapshoot. You don’t get in based on dreaming.