In reality if you were going for the ultimate save file you would use god mode leveling up and down to get maximum of every stat for every character. Don't know who would do this, but just saying...

(For those of you who didn't know, I'm referring to de-leveling your characters in job classes with poor stat growth then re-leveling them in classes with good stat growth, several times)

As for me all I ever did was do all propositions and have all my characters at 99. Whenever I get the urge to play the game more I usually just end up starting a new game using different job combinations.