At many events where they have a sign language interpreter signing what the speakers are saying they have two interpreters switching off because it is so intense to sign and each one needs a frequent breather.
I would think being ATC and interpreting all of the blips on a screen is intense and breaks are needed.
It seems like it would be a good idea to be regularly a little it overstaffed at the tower. Directing air traffic is, after all, a matter of life or death.
What if an ATC gets a migraine attack? Or gets a call that there is a family emergency?
This was the Tower, it has a 5 mile radius. Clear night was all visual. Approach Control is the 'blippy' job.
Good points on ATC staffing!