It might be exciting to have intermediate steps, each one creating a potion which is useful on its own, but even more useful in a later/final form, like the steps of the Magnum Opus. Of course, if one had to go through multiple steps to get the final product every time one needed more, it could easily become tedious. So, there should be some way of automating the steps once one has done it once (like fast travel).
Or a potion might need to be mixed at the same time it's used, so creating a higher level potion would be impracticable in a fight, unless one has cover. Then, I don't know that this is supposed to be that kind of game. But this kind of mechanic may still be applicable outside of combat.