Example: several of my former coworkers are from Mexico, Peru and Argentina, meaning they share Spanish as a common language.
I used to practice Spanish with them, but my last charge (like a ward’s manager) would yell at us to stop it, use English only. She would get very angry really fast if she heard anything in a language she didn’t understand.
I find it stupid, because some of them would use Spanish to better explain to the new nurses how to do certain procedures, but maybe I’m missing something?
Let people communicate however works well for them. Especially, if it increases speed/productivity. And even if not, it will raise workplace morale, which in turn will most likely increase production again.