Software may be employed to do pairings, and in the early rounds it will match teams with approximately the same score but it will not result in a precise 1 vs 2, 3 vs 4, etc. This is done so that matches can begin before all teams have finished the previous round. In later rounds, the pairings are slower but more exact. In the last one or two rounds there may be a switch to the Danish system to make sure that each team plays the final match according to its actual ranking, even if this results in some teams playing against an opponent a second time. At least in the US, this is extremely rare, usually employed only in small club games with a large number of rounds relative to the number of teams.