Then you don't do any subjects at a higher level, as you aren't doing any Advanced Highers. Just the rote-learning, low-content Nat 5s and Highers.
And as already discussed, it's very common to do A, B, C, D, E, F subjects at Nat 5, and then the same A, B, C, D, E subjects at Higher - so you're only studying a small number of subjects. At GCSE level, people study up to 12 different subjects. They then move on to study 3 subjects at A'level. Those subjects may be the same, or they may be different (for instance psychology or law).
My DC wanted to get into a decent uni, which meant taking some academic subjects - at Nat 5 and then following through to Higher and Advanced Higher. This meant that they weren't able to do any fun, creative subjects - music, art or drama. It also meant that they were forced to choose between the sciences and the arts and languages or humanities subjects very early. Whereas in England you can do everything until 16, plus a couple of fun subjects, and only specialise after that, at A'level stage. In Scotland you really need to make the sciences or not choice at 13, but in England you can make it at 16.
So I was very struck by how restrictive the education was - it was particularly bad having to choose between sciences and not at such an early stage, ending up with very little scientific knowledge and risking making the wrong long term choice. And DC was pretty sad about not being able to do any fun subjects.