With the arrival of NIL and portal hopping, it's pretty hard to retain players long enough for them to master the pack line.

I told my dad this summer that if I were CTB, I'd sit down with Jim Boeheim now that he's retired and learn all I could about his famed zone. That would probably be a challenging one to learn, honestly. But you can do a lot of things with zone D. And it's easier to pick up, imo.