Normally the number of rounds is four. Sometimes (especially in tournament rules) the number of rounds is increased or decreased.
In Four Winds you can set the number of rounds to any number between 1 and 16. Notice however, that specifying a number that is not divisible by 4 is often unfair to players whose rounds are never played (players don't have the opportunity to collect "double winds", i.e., a Pung or Kong of Winds, where the wind is at the same time player's own wind and Wind of the Round). If you change the number of rounds, you may want to zero scores for Wind of the Round.
Using five sets
Round wind sequence
Specifying how discards are placed on board
Using extended discard information
Pass deal after East's win