I have always found it useful, especially for mid-high level wizards to have multiple prepared spell lists. Nothing slows the game down more than when the party rests and the wizard decides to swap out all their spells. Instead, I like to have an A list, B list, C list of favourite combinations of spells and then a few variations that might be themed e.g. a list that supports clandestine activities or forest vs. city - that sort of thing. With these in place, swapping out spells is a breeze. You can toggle from your A list to your B list etc. Or, if you need your City list but need to swap out just a few spells it is much easier. Automating this system so that players can easily swap from one pre-prepared list to another would be awesome!
