In UChicago’s case, the percentage of “large” classes also is rather low (5.5% >= 50 students).
That’s one of the lowest percentages for any RU, but still higher than many LACs (which in many cases have 0% >= 50, or even ~0% >= some smaller number). My S2’s LAC claims that class size is limited to 25 students (unless the class is taught by 2 professors, in which case it generally is limited to 32).