The U consumed in Shuan 15 minutes and Shuan 16 minutes should differ by a factor of two. The U consumed in 15 minutes for a month is 50, while the U consumed in 16 minutes for a month is 100. In a month, Shuan 16 minutes can earn one more coin compared to 15 minutes, but currently, the probability of earning one coin that can be sold for more than 50 U has decreased; most are sold for less than 50 U. Therefore, whether to Shuan 15 or 16 times a day depends on yourself.