Most of my courses beyond freshman year were 10-20 people where I basically know everyone (unless they never come to class), so I would know if they weren’t showing up at exams. I’m pretty sure if these people were evenly distributed I would notice every exam for every class missing 1-2 people. So this is not it.

It really depends on the environment tbh. I know just for the "low distraction environment" accomodations, those normally aren't used for small classes but they are used for the big exams where they stuff the entire freshman class in the program into a series of auditoriums.

And of course some professors do double time accommodations by having the students take the test with everyone else and then follow the teacher to their office to finish the exam afterwards but tbh I didn't see that very often.