As soon as I leave Balamb for the Fire Cavern, I grind until I have Card Mod. Then I card the Fasticholan-Fs until I get a few Status-Js for both Quetzacotl and Shiva. Then I card one of every enemy on Balamb island and then I basically stop carding for the rest of the game. I finished the game at something like Level 80 because of some level grinding somewhere or other but generally it doesn't matter. Junctioning is the most important thing and Rantz is a lameoid for trying to make the game easier.