Different schools teach differently. I think Clarissa has had a poor experience with her dcs' school 
Ds' school sets in Maths and English from S1 (they may have changed recently to a later year to set for English for educational reasons). Friends whose children are at other schools are also set, both in Glasgow and elsewhere.
Good teachers will always stretch their pupils. Ds' maths class (top set) was consistently about 4 months if not more "ahead" of where they needed to be (eg started the Higher curriculum well before sitting their Nat 5s). One lad sat all his Maths exams a year early (so did his AH Maths in S5).
There are both pros & cons for the Curriculum for Excellence ( sofiesworld won't know what CfE stands for
). One of the pros is that it is supposed to be less about rote learning and more about how to apply the knowledge. In Maths & Physics that means IMHO, it is actually more difficult than when I did the subjects (many many
moons ago). Despite getting As in both subjects at Higher, I struggled with "applied" Maths and "applied" Physics - so would really struggle with today's versions of the exams (notorious questions of crocodiles crossing a river with a current in Maths and nasty questions which actually involve probability). Ds is doing stuff on Plank's Constant for his AH Physics which goes way over my head. Ditto with his AH Maths.
Geography on the other hand does just seem to be rote learning - and ds' teacher advised him if he wanted to do Geography at Uni not to do the AH as he would then be bored in his first year at Uni.
If you look at UCAS tariff points (presumably a neutral, even actuarial, adjudicator
), an A at AH has the same number of points as an A A Level
A B at AH is worth the same as an A at A Level. An A at Higher is worth 33 points - significantly more than AS Level which is also sat a year after GCSEs (I realise that AS Levels are being phased out / no longer encouraged) - and a point more than a C at A Level
* So as most of the academic pupils will do 5 Highers in S5, that's a really good foundation for Uni applications
.
Ds has chosen only to do 2 AHs and is crashing a Higher in Modern Studies alongside them - just as well
as he changed his mind over the summer about what he wants to do at Uni (from Maths/Physics to International Relations/Politics. He already has 2 Unconditionals (Aberdeen & Strathclyde) but is still waiting to hear from his preferred choice, Edinburgh. He is not unusual at his school.
So my experience of Scottish education (and that of my friends - including ones who've moved up from England) has been a positive one 