Okay, I was an undergrad at Stanford a decade ago, I graduated with two majors (math, physics) and almost another minor (CS) so I took more credits than most and sat in more tests than most, and I don’t think I’ve seen a single person given extra time on tests; and some of the courses had more than a hundred people in them, with test takers almost filling the auditorium in Hewlett Teaching Center if memory serves. Article says the stat “has grown at a breathtaking pace” “over the past decade and half” and uses “at UC Berkeley, it has nearly quintupled over the past 15 years” as a shocking example, so I would assume the stat was at least ~10% at Stanford a decade ago. So where were these people during my time? Only in humanities? Anyone got first hand experience?
Testing accomodations are generally done at a separate time. So students with an accomodation requiring a low distraction environment or extra test time would all take their test after the main test takers.
This came with the dual advantage of providing an alternate time for students who had excused absences to take the test as well.
TLDR: You don't normally see the students with accomodations during tests unless you also have an accomodation or you had a conflict with the test time/date.
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.