A large part of the main boxing stars are fighting once a year or once every 2 years.

A large part of the main boxing stars are fighting once a year or once every 2 years, many of them are world champions, that is unsustainable. Canelo is probably the biggest star in boxing and he is the one who earns the most money and he always fights 2-3 times a year, why can't the rest of the boxers do it?