This is something that has not been officially confirmed but there are helpful players out there who have tried to measure the time that it takes for a full day to go through its cycle at school. From what some have time in the past, it can take close to 17 minutes for an entire day to go through at school. We presume that it could take anywhere from about 15-20 minutes for an entire day to pass and it ultimately depends on the school that you are attending at the moment and the actions that you do. Minigames and how long players take for certain actions like the ball could affect the length but not by too much.