The very best teacher I ever had was my calculus teacher, who was teaching it for her first year, and although claimed she had trouble with calculus, was a truly gifted teacher and an enthusiastic “math nerd.”
The shtick about being bad at calculus, whether true or not, translated into a highly Socratic and collaborative learning environment, where all the students were legitimately teaching each other. This was modeled by us “teaching” our teacher.
Thinking back, it really is incredibly remarkable what she accomplished. Not that standardized tests are the greatest measure, but in less than a year of calc instruction, a full classroom of smart but fairly unremarkable students all scored top scored on the AP Calc BC test (in other words, every single one of us tested out of 100-level college calculus).
This was a scenario where having a “large” (ie more than 1-5 students) class (I think there may have been about 20 of us) with a gifted teacher brought out a positive side to non-small classes that you don’t usually see. We all learned the material well enough to teach it, and we all had many teachers we could go to for help understanding a concept.