[8note]

I had split 3/4 and 5/6 classes, where you stayed with the same teacher and students for both years, with either an older or a younger cohort with you to fill out the other grade

Theres at least one benefit outside of having a good teacher for two years - - the teacher starts the second year with context about your skills and what needs improvement. Eg. They can spend the summer knowing how many students are ahead and plan relevant coursework

The downside was around not interacting with the students who have the other teacher much for a couple years. Much harder to retain those friends

[lumost]

This assumes that the teacher correctly identified what needs improvement, or cares to improve you. Neither of these are given. My recollection of school was that I was often miss-understood by teachers resulting in net-negative interventions. Sometimes I'd be fortunate and click with the right teacher. In aggregate my current success depends heavily on those few times I clicked.