during the tri nations era, the contest began in july, during the southern hemisphere winter, and ran through september. for most of that era, each team played every other team twice, once at home and once away. later on, each team played the others three times. when the competition added argentina, it returned to a pure home-and-away format, with a total of 12 games played. also, due to a slight change in the sport's calendar, the rugby championship now begins in august and runs through october. this format is used except in years in which the rugby world cup is played (every four years, in the year before the summer olympics). in those years, each team plays the others only once, with a total of six games played.