How much time is needed for formal group shots on the wedding day?

How much time is needed for formal group shots on the wedding day?

I don't have any traditions or formalities when it comes to photography, especially wedding photography. As for formal group shots on the wedding day, I only arrange those which are requested. Before the day, I contact my couples and ask them to think about what group shots they really want, if I'm going to start directing and moving people around, and more importantly keeping people from the bar! Then I want to make sure it's something my couples are actually interested in and want.