I think the hardest part of healing is that what becomes the most effect approach to a fight can change drastically based on what your party does. White Mage has the least amount of optimization as the healer with the simplest kit but even still there are a ton of ways to conserve MP or manipulate resources that can make the difference between a wipe or clear. Being able to pass a heal check is not difficult without the outside pressure of low MP from party rezzes or recently being revived or a dead cohealer. Experience with recovery from failure is more important than practice spamming Cure 3 and it's hard to create that in a controlled environment.