i was wondering what do you mean by students are rewarded for extra detail in subjects like physics? I thought physics marking guidelines were pretty strict for what they want you to say in short answer right? same with chemistry. so going into too much detail would probably produce a convoluted response.
well for example q21 in 2023 hsc physics, you were asked to identify two variables that determine the luminosity of a star. most students are only exposed to the HR diagram so would have probably written the size and the temperature. however, the power output is a variable that also determines the luminosity, and this isn't in the syllabus, but is still a fact that is rewarded. The formula for luminosity is also not in the syllabus, however it is a very good idea to know this and I'd say many physics students probably know this anyway because of questions like this and other relevant formulas to stars that aren't in the syllabus (i did memorise the luminosity formula myself).
question 33 in 2023 hsc physics is another example. it pretty much asks you to list off experiments related to quantum physics and/or particle physics that made new discoveries in these areas, and how these experiments relate to fields. a student with out of syllabus knowledge could talk about the higgs boson, discovery of quarks, etc. and be aptly rewarded (and afaik some schools also teach these concepts), just as much as a student who would talk about thomson and the electron, chadwick and so on.
my point wasn't so much that every single question has an out of syllabus response, moreso that if it does, students are still rewarded for providing one and this is sometimes even in the marking guidelines like q21 in 2023 physics, so i don't see why math should be treated any differently with regards to out of syllabus content