Final exams: What is the most common protocol for scheduling?
In the two major US state universities that I have either been a student or taught in, the process was roughly the same:

Final exam times were based on the first day of the week course time for the main course meeting, typically a 'lecture' section. Every course that started at 9am on a Monday had the same final exam time. Every course that started at 11am on a Tuesday had the same final exam time. All these decisions were made centrally.

The exam times were mostly unrelated to the actual course times, since the final exam slots were longer than the actual class meetings, but it ensured that no one had overlapping final times because no students would have two courses that met at the same time. The exception was courses that were specifically night courses, which also had night finals, with the assumption that some proportion of the students in those courses were not full-time students and may have had other daytime responsibilities.

I believe there were procedures to allow for simultaneous finals for courses with multiple sections, but I am less familiar with how those processes worked; I believe the centralized time was chosen and then arrangements were made for the small number of students for which there was a conflict.

There were also processes for students who ended up with >2 finals in the same day to make alternative arrangements, but again, these circumstances happened rarely, especially because not ever course actually utilized their final exam slot as anything but a due date for a paper/project/etc.