When I was a grad student, we had group finals for calculus (i.e., standards uniform across all professors/TAs). We did not observe any statistically significant difference in grades between professors or (professor, TA) 2-tuples.

We were planning to use grades as a better way to evaluate teaching quality. When it didn't work, the professors (1) decided to go back to student evaluations rather than admit their job didn't matter.

(1) The people in charge of undergrad teaching were faculty not actively doing research, but who did have an interest in teaching well.