According to the traditional view, the more the best man works, the lower the fate, and it is difficult to find a partner and girlfriend in the future. Therefore, in the traditional view, people can't be the best man more than three times.
In fact, this is also left by folk customs, but there is no such requirement at the wedding, but the best men we meet are often unmarried.
On the one hand, married people don't want to be the best man, mainly because their lives are similar, and on the other hand, they take care of their family's feelings. After all, being the best man needs some interaction with the bridesmaids. Some people don't want their lover to associate with other women in their hearts.