An idea for vancian magic

"Everytime you cast a spell, instead of losing the spell you just casted, you cross out any other spell of the same or higher level instead; unless that was your last available one, in which case, you lose that spell"

It doesn't really fix my quest for the perfect magic system, but it feels like an improvement towards the original: Now you can use the same spell more than once per day, which is how you would expect magic to work in any fantasy setting (except, of course, Dying Earth, from which vancian magic is taken). If I see a wizard casting a fireball, I would prepare against another fireball and try to close range with him as much as possible, so he cannot cast another one on me without hurting himself. In the D&D world, however, you are completely safe from another fireball, as you are sure he cannot even prepare the same spell twice.

Also I like that you can explain it as making the spell you cast becoming more and more present in your brain the more you cast it; the obsession feeding on the other possibilities you had prepared (the rest of the spells)

The problem I perceive is more "conceptual" than "gamist". But, on that side, it allows you to prepare a lot of absurd spells and burn them away once you feel that you are probably not using them that day. That, while using the ones you need without being unnecesarily stingy. I also like that it doesn't change the game at Magic User's level 1, but can be a gamechanger at level 3 or higher: Each new spell gives you much more possibilities on every rest.

EDIT: As you can see on the comments, I have been mistaken all my D&D life, and MUs can prepare spells twice (nowhere mentioned explicitly on BX but I was just assuming they couldn't). This is why its cool to have a blog, I'd still play like that if I hadn't talked about it here. STILL I think my idea is useful to allow casters to spam the same spell multiple times, while still giving them variety of spells at the same time. Are they too OP? maybe.