People who are saying 12 or even 13 GCSEs suit their children don’t really know, though. It is not as if they can compare what their children would have been like if they had sat fewer GCSEs.
Within the educational community, though, a lot of schools who used to be in the race to sit huge numbers of GCSEs have removed themselves from it, and some even from the league tables, believing that there is more to education.
Even one of the exam boards think that the Idea of the more the better is overdone.
https://www.bbc.co.uk/newsround/articles/cwyj0x1dje2o
As I said on this or another thread, one of the most academic private schools in London used to do double award science, not because they didn’t think the pupils couldn’s easily achieve 9s in triple award, but because they wanted to go narrower and deeper, knowing that the students who pursued science could easily catch up the extra content over the summer hols.
No one who has chosen a school which does 12 GCSEs is going to say it is a bad idea, especially if their children are on track for great grades, but I doubt many will be doing that many in 10 years time, regardless of ability.