Without knowing more detail, my best guess would be that the crew wanted a chance to grab something to eat. If they arrived after scheduled departure time, they must have been delayed... It's entirely possible that they lost any break time they had between flights throughout the day, and needed to take a moment to get nourishment to continue their day. Speaking from experience, I highly doubt that they used the time to sit down and lounge... They almost certainly wanted the time to attend to physiological needs.