I don't think it's cheating, though it's quite a cheap tactic. I never bothered to level up the Change spell so I never used it, and in my game of FFII DoS, my party members' HP kept automatically leveling up, so I didn't need to attack my own party members. I can't remember what Anti does or if it's the same as Sap, but I kept using Sap on my own party members to drain their MP so that they could gain more MP that way. I just thought the way of casting a spell dozens of times on one battle to waste your MP was way too time-consuming and stupid, so instead, I used a spell that lowers the target's MP.