For first round offers thats totally incorrect. They come out in a single round.
Towards the beginning of the school year if they still have a couple spots open, schools have been known to call up the very borderline students asking if they can immediately start and in those cases, the students that say yes would get accepted.
However this only applies to a very small handful of students, and only a very small number of circumstances. I'm not sure if ive heard of UQ doing this, in my time at UQ it also doesn't sound very UQ-esque. They're more of a twenty-people-email-chain-and-subcommittees-fustratingly-slow-administration type.
UQ IIRC last year was 3686 total score. I think it's not super likely to rise overly dramatically, so as long as you can get yourself over that 99 rank (including bonus points) then you will get in. The 99 is a hurdle, so a 99.05 has the same chance as a 99.95
*unless theres a tie-breaker, in which case UQ's tie-breaker algorithm is published somewhere on their website.
Congratulations on the fantastic UCAT, and good luck.