Pupils deserve the best standard of education in every area of the curriculum. The days of the well meaning junior school generalist teacher are drawing to a close. To survive, prosper and enthuse, teachers need to have complete command of all the subjects they teach.
My recommendation is that junior schools split teachers responsibilities into either Maths, Science, Technology & Computing Science (Maths & Science) or Literacy, humanities, digital literacy and the creative Arts (Literacy & Humanities). Each teacher would teach two tutor groups the same material adapted for the individual needs of the pupils concerned. Many pupils in Junior school are already taught by a team that includes teacher, classroom assistants and learning support assistants, extending this team to include two teachers will not weaken teacher pupil relationships. In larger schools, where there is more timetable space to adapt, teachers would share classes across the same year group. Smaller schools might find teachers teaching more than one year group. Teachers would have less subjects matter to teach and half the planning, leading to more time to keep up to date with current practices.
Teacher training colleges would need to adapt training to reflect this new system. OFSTED would need to widen its scope to meaningfully evaluate a wider range of subjects than just Maths and Literacy. In my opinion this narrowing of importance to just Literacy and Numeracy has been one of the greatest disasters for primary pupils in the last decade.
If you teach in KS2 would you like to teach in this model? Or are you horrified by the idea of losing the generalist teacher role?