idk why I been seeing HUA on a lot of these forms but personally I strongly disagree with their view on spec.
Methods and spec are manageable if u put in some work and enjoy math. They overlap a fair bit so circular functions, algebra and in year 12 calculus, graphing and algebra will all overlap a fair chunk.
HOWEVER there is an important note with doing 3 math subjects. With the ATAR calculation, the big 4 SS are ur English SS and ur top 3 SS. However they do not allow u to have 3 math SS in ur top 4. SO if u end up getting a 50 in spesh, 50 in methods, 50 in general, 50 in english and a ss of 10 in chinese, they will take chinese in ur top 4 and leave one of the other ones behind despite ur good score. it is because of this that doing all 3 is kinda useless, I feel like a combo of spesh/methods workers better as they overlap and often have the same teachers as opposed to general. Most teachers who take spesh r super smart and can help u with methods as well so there is also that. I have written alot about why I enjoy spesh so u could look through some of my past posts or really just search around the forum there r many people who have asked this question and had opinions provided.
One final piece of advice, don't do spesh for scaling. It helps, but that can't be ur only reason.