True stories:
A wanted to get into medicine. Got 98.xx, and not a high enough UMAT.
Repeated year 12, absolutely worked her arse off (I'm talking the no-extra-curriculars-no-social-life kind), got approximately the same UMAT score and 97.xx (I'm guessing she burned herself out...).
She did biomed and didn't get into graduate medicine.
B didn't get a high enough UMAT (don't know what her ENTER was).
Accepted offer of biomed but deferred the year and spent it working on the UMAT (she's the kind of person who doesn't take no for an answer!

)
Killed the UMAT and is now in 2nd year medicine (she was in my cohort, so she's a year behind).
C got 89.xx which wasn't enough for her dream course of science/law, so she went into science and absolutely killed her first year (high HD average). Transferred into science/law in 2nd year which means she hasn't wasted any time/credits at all - she'll just graduate from science much earlier than law.
Currently has a law average which is higher than mine (NB: I got 99.xx for my ENTER) and enough to get her first class honours if she keeps it up.
These are just the stories I personally know. I've heard of many more people like A and C, but second hand so I can't verify them.
Please don't waste a year... people like B are a very tiny exception...