But Highers, in addition to doing more of them, are usually done in only one year (which is what the universities prefer) - at least for the academic kids.
Ds' school was one of those that does 8 Nat 5s (by choosing at the end of S2) and ds ended up with 8 Nat 5s and a Nat 4 (in RME). If he hadn't been doing PE as a Nat 5 (and had done, say, Art instead as I think that in the same column), he'd have ended up with 8 Nat 5s and 2 Nat 4s as he'd have been awarded a Nat 4 in PE (not that I'm suggesting that Nat 4s are particularly wonderful - not even sure they're still awarded
)
And then, like the majority of the academic kids, he did 5 Highers in S5. Even though we don't officially have rankings in the same way as England, the number of pupils who get 5 Highers in S5 is one of measurements that people use to judge a school.
Interestingly, Advanced Highers are worth more UCAS points, grade for grade than A Levels 
(iirc, an A at AH is worth the same as a A* at A level and a B at AH is the same as an A at A Level).
Ds' school has a lot of experience of pupils coming from countries all over the world (including England
) and it has always viewed GCSEs/Y11 as roughly equivalent to Nat 5s/S4.
I agree about the jump from GCSE to A Levels - it's one of the things that Curriculum for Excellence was intended to address in Scotland: ensuring the jump to Highers wasn't so severe. Iirc, it was even intended that academic pupils would bypass Nat 5s entirely and go straight through to Highers - although very few schools actually availed themselves of this (maybe only one? - and even if it has stopped and now does Nat 5s). (Personally I agree as otherwise it would be a tremendous shock to the system if the first exams you encounter are the important Highers
)