I have used the term ‘Floater’ before. It is a simple construct. A person is hired who can do what is required when required.
The floater can work a cash register, can go in the back to locate goods. A floater can answer a phone or make a call.
The floater can be a manager until such time as a worker is needed.
The Floater, (or all rounder if preferred) is more or less groomed for the highest positions.
Being aware of this makes even the most conceited perform menial tasks.
Once one knows what the task entails, has performed it, more than once, has seen the ups and downs, weak links and the strong ones, they get a truly enviable list of skills.
The other ‘up side’ is that customers are not lost because Cashier A is missing or there is no one to go into the store room for the product, or this counter is ‘unmanned’.
This ties in with having one less worker than needed.