Quote from my wording, which bit you are referring to. Because you are using an imprecise wording that covers both sorts of thing that are available from the stadiums, *one* of which is required to progress. Edit: Or you are just restating what I already said?
Beating the three individual races is required to progress. That I've done (otherwise I wouldn't have the Extreme tracks unlocked). Beating all the 3-heat back-to-back finals is required to unlock the Grand Finale. That I cannot do. All the previous ones I did in one or two tries, but this last one is fucked.