My favorite example is that of a restaurant. You hire waitors, diswashers, bartenders, line cooks, prep cooks, hosts and hostesses, and managers. And your waiters might be 100% focused on taking orders during prime dining hours, but at the end of the night, they help clean up assuming other roles. Your bartender might be busy making drinks, but they take a table or two if they can. Your prep cook might finish the prep early, and come on the line to help out. Your manager focuses on expediting everything and keeping the ship running smooth, but also can fill holes at time.