The superintendent reports less stress for teachers. Apparently this was because it reduced teacher workload as they were now planning only two lessons a day instead of five. So much for personalisation of learning, apparently you can take the same lesson and teach it to several different classes without needing to make any changes to meet the needs of the learners in those classes.
Now I can see how using teachers with specific subject area strengths for some sessions could work but I would see this happening on a needs basis. Students would be working on their inquiries and experts in areas of need could be brought in to provide specific, targeted help. Or in a modern learning environment where classes have more than one teacher there could be some specialisation, again based on student need.
Putting subjects into silos in primary school is a backward step in my opinion, I would like to see more curriculum integration, not less. I believe in curriculum integration where inquiries naturally take in a number of curriculum areas and subject specialisation makes this difficult to happen. In fact it is one of the reasons a lot of high schools struggle with student inquiry. I am not saying it can't happen, there some high schools doing a wonderful job with this, but a lot of planning and collaboration between teachers is needed to make it successful.
“The values, competencies, knowledge and skills that students need for addressing real-life situations are rarely confined to one part of the curriculum. Wherever possible schools should aim to design their curriculum so that learning crosses apparent boundaries.”
(N.Z. Curriculum p. 38)