Competition has been mainly restricted to participation in weekend tournaments. Weekend tournaments vary in size and format, but as the name implies, the competition generally consists of a lot of games over a 2 or 3 day weekend. Depending on the format of the tournament games may be shortened to 2×20 minute halves to allow for more games in a time constricted weekend. Often a tournament will consist of two pools of 3 to 4 teams, with the top two teams from each pool advancing to a semifinal crossover, with the winners advancing to the final. Currently, there are no organized leagues in the United States. A number of reasons can be attributed to this shortcoming, but the biggest factors are the small number of clubs and the geographical distances separating them which makes frequent travel for games expensive.