Also some teachers are better than others! I think two year in a row can have advantages. But different teachers bring different perspectives and different strengths. Sometimes a teacher will magically click in some way with your child and bring something out of them that other teachers hadn't managed.

I remember having the same English teacher (as in English literature) for five years (slightly accidentally - we got randomly allocated a couple of times and I ended up with her each time) and I think it gave me a rather narrow view of the subject.