A wizard then should have a spellbook, one filled with all sorts of spells written out for immediate use. Maintainable hacks if you will. Those are probably just scripts though I suppose?
What is needed is an artifact like spellbook, that the wizard when faced with a situation could describe it to the spellbook and get back the correct spell or combination of spells to solve the situation. Attempts have been made to create such an artifact, but unfortunately the resulting spellbooks still take a long time to find the correct spell and when reading the spells you often find that there are missing ingredients or a complicated set of gestures that must be performed to make the spell work, and you have to read all about these gestures in turn to figure out which ones you really need.