I'm in the ME, teaching. Everyone has been wearing masks for months. They are mandatory for students except during breaks, when each year group has a socially distanced area & clearly marked places (stickers 2m apart, with a chair unless it's the bleachers by the pitch or the external steps in the main quad so they can already sit down) for mask removal.
It's fine. I only get irritated by mine now if I'm teaching from the front of the room & talking for extended periods.
Exams absolutely justify mask wearing - anything up to a couple of hundred kids in a gym or hall with no open windows, desks far closer together than 2m & invigilators walking between the rows & needing to get right up close to the kids to whisper.
Also, bear in mind that invigilators are either hired in (UK) & often older, vulnerable people earning peanuts OR overseas it's often the teachers. The outside invigilators are likely to be harder to hire this year. The teachers are not in whole year group situations at the moment normally for obvious reasons eg no assemblies. Invigilation is a high risk activity.
Last week a member of my Dept was isolating pending a test as he had potential symptoms. If he'd been infected, that's the whole Dept out as we share an office. This would have closed the school as we couldn't all have been covered for two weeks.
If you'd like the actual exams to go ahead (& I reckon that's quite unlikely anyway...) & the kids to be taught in school from now until they sit them, you do NOT want a spike in the numbers of infected/exposed teachers just after Xmas. Or it's Game Over.
So it's masks on & crack on. Any students who have a medical reason not to wear them can be accommodated in separate rooms. Oh, & that means a need for more invigilators, & more exposure of invigilators to potential infection. But it can be accommodated for those students for whom it's a genuine need, if everyone else stops taking the piss & just wears the bloody things.