My dad read comic books to me very night when I was 3-5. After that, I read to him until I was about 8. I graduated from “Sad Sack” to “Classics Illustrated” on to “Phantom Stranger” in that time and my reading comprehension (which was tested every semester) was off the charts. Teachers were actually borrowing my comics to teach other kids. You’re right; it’s just the practice and those gave us plenty of practice that we enjoyed.
The cool thing about comic books was trading them. We always had a stack.