USA
I used to work in Chicago ARTCC where we had a position normally staffed by:
Radar Controller
Coordinator/Supervisor
Tracker
"D" Side
Assistant
It could get crowded around the scope!
In Denver ARTCC right after the PATCO strike we worked mostly one-person sectors. One day I developed laryngitis and lost my voice. Since there were no controllers to take over the sector, I slid over and we plugged in a new assistant controller, a guy with no experience at all. I wrote clearances on a scratch pad and the kid transmitted them to the planes.