That's a terrible example, because getting a 94 in 2U is immensely easier than getting a 94 in 4U.
Theoretically, you can drop 4U anytime up to the Hsc exams, even a week before (correct me if I'm wrong).
I suggest doing 4U as a subject, and keep it (if it's not too difficult) at least until after the trial exams. After the trials decide which maths you are going to go with.
Doing 4U makes your 3U mark so much better, and makes 2U seem really boring. It is however, a lot of extra work. It's a balance thing, you just kind of have to work it out for yourself to see what works for you.
Theoretically, you can drop 4U anytime up to the Hsc exams, even a week before (correct me if I'm wrong).
I suggest doing 4U as a subject, and keep it (if it's not too difficult) at least until after the trial exams. After the trials decide which maths you are going to go with.
Doing 4U makes your 3U mark so much better, and makes 2U seem really boring. It is however, a lot of extra work. It's a balance thing, you just kind of have to work it out for yourself to see what works for you.