Yes. My one, nearly complete playthroguh had me go to this cave I think after Leila joins your party. In this cave there was a Gigas enemy, the first time you can run into them as regular enemies I think, and it kicked my ass something fierce. So I spent a good long time grinding up Magic for my party because physical attacks weren't doing jack.

And then when I got Ultima I got it to Level 10 or something and stopped.

I don't think I ever got any spell to Level 16...probably Level 12 was the best I got with Cure magic and the regular attack spells.