I’ve spoken to a lot of uni admissions staff for a range of subjects. All highers are not equal.
I’d start by looking at whether the uni course is academic or not and how competitive it is. This should guide you as to how many ‘respected’ academic highers your child needs to take. You couldn’t get away with practical cake decorating as an A at higher to get into maths at a proper uni. For a course in something more practical you would.
Maths, physics, english, history, biology, chemistry, computing, geography, languages are respected as proper academic courses.
Engineering less so (too similar to maths and physics), graphic communication, modern studies, business, RMPS, psychology are less academically respected too.
More practical but show application art, music poss PE.
Not useful for uni cake decorating, application of maths.
To get into a hyper competitive degree you need to be doing at least 4 academically respected subjects, preferably 5. If something is less competitive you have a bit more flexibility.