(Thanks, OOTS.)
It strikes me that the Wizard really wants a move that goes something like this -
Always Prepared: At the beginning of every session, roll+Wis. On a 10+, hold 3. On a 7-9, hold 1. You may spend this hold during this session to cast a minor spell effect (Bugsby's Cat-Retrieving Hand e.g.) not on the spell list.