What if we want to have an accessory that teaches slowly, and a shop that lets you learn it instantly (at an insane price, mind you!) It might be better to build everything with the assumption that it requires AP (or an equivalent), and just let people override the slow learning with 'Jump to 100%' items/shops/equipment.
This is not at all related to my fiendish plan to make the spells the player purchases only have 20% power and effectiveness, thus forcing them to grind them up to full strength. Not at all.
<_<