There are three periods. The first period is when the gym just opened in the morning. There are almost no people in the gym at this time, which is also the best time to exercise. The second time is noon, because most people eat and rest at home at noon. At this time, there are relatively few people in the gym, but there will not be too few on weekends. The third time was an hour before the gym closed. At this time, the number of customers is gradually decreasing. Most of them leave after practicing, which will be slightly less than that at noon, but the subject may not finish practicing or miss the shower, so the subject can choose according to his own situation.