And just to be clear, I'm only recommending the "free" approach when you want to maximize your GPA for professional schools, such as dental, medical, and law school (although law school is a complete mess at this point).

I don't know whether the same approach is used for Ph.D.'s since my experiences and my DW's family's (free/massively subsidized undergrad) experience consists solely of psychiatrist, dentist, lawyer, etc.