Compared to Hajime's class wherein the groups were equally divided, Natsumi's class was different. In fact, it's pretty much 'anything goes' regarding their class's school trip. Their homeroom teacher, Hirano Tetsuo, couldn't care less whether they get lost during the school trip or not— totally unlike Akamine-sensei's ideal which was to constantly worry about her students.
Of course, Tetsuo still implemented the school trip schedule since he didn't want to deviate from it that much. That would certainly get him in trouble despite having full jurisdiction over his class— meaning he could change anything in the schedule and it would be fine as long as it's in the vicinity of Tokyo.
So instead of changing the schedule altogether, Tetsuo decided to give his students a little bit of freedom by making their free time, well, a legitimate free time. They could do whatever they want and they could go wherever as long as they asked permission first.
