not really, if you got a uai of 90-95 doing no math/science at all and you're not good at math, you'd be pretty stuffed if you tried to major in math or physics in science. Similarly if you did a lot of math and sci but only standard english(and did poorly), you'd struggle quite a lot with more artsy subjects like history or comparative literature.
a lot of people I know who do law struggle to keep a good average because they got the high uai by doing mostly high scalling math/sci, and a lot of engineering/science people I know struggle because they didn't do much math/sci in the hsc but they got in because their uai was high enough.
oh and I got a uai of 88 and i'm in a science degree with an HD average after 2nd year