meaning their obligations to their profession varies at all hours of the day and all days of the week (ie. charity events, filming, travelling, promotional appearances, etc.) whereas for a lot of us, we'll miss a game to go to dinner or a movie with a girlfriend or wife
for example, if Billy Cystal is filming a movie for 3 months in Los Angeles, it would make sense that he wouldn't travel to New York to take in the Royals