Hi! I think it mainly depends on how much effort you are trying to put into the HSC, since although these enrichment levels may occur in the harder sections of your school exam and the HSC, they don't take up the majority of the exam. Most of it (assuming Advanced/Extension 1 Maths) is slightly repetitive and solidifies your understanding but understanding all the concepts that could be examined is often more important.
There is always going to be value in doing more questions, however, if you are getting "tumours" from trying to solve them, I suggest you prioritise your health first; there's no point in doing more questions if you are pushing yourself too much (a little bit is good but too much is excessive).
Hopefully this answers some of your doubts, and to reiterate, it just depends on how well your health is doing/how much effort you are willing to put in. For example, there's not really a point of getting like an 99 atar if your degree doesn't require such a high atar and you feel detrimentally impacted by the journey you made in getting there.
Take care and wish you all the best with your studies! Have a nice day
