Where I am in Australia there are four terms, about 9/ 10 weeks each. Terms 1, 2 and 3 have a two-week break each, and the summer holiday is 5 and 1/2 weeks. It works very well, you really get to de-compress over the two-week breaks, far better than the week's half term of the UK.
For context, since PPs have mentioned it, exams are a state monopoly, only one exam board and all exams marked and back before the summer holidays. Uni applications are late in the summer holidays. Another significant factor is that there are no exams at 16, only at 18. This makes huge difference, and having taught both streams, the Victorian model is far better, you really don't need the GCSE.