 Additionally the dancers may be asked to perform further solos in styles of their choosing and participate in a group choreography round in which small teams of contestants must display their musicality and ability to communicate professionally by choreographing a performance to a randomly selected piece of music — this challenge is notable as being the only time competitors are asked to choreograph themselves, aside from solos.The callbacks are often collectively portrayed as one of the most exhausting and stressful stages of the competition; each successive round sees cuts in which a significant portion of the remaining dancers are eliminated from competition and are given a limited amount of time to adapt to styles they are sometimes wholly unfamiliar with while being physically taxed by the rapid progression of rounds and a limited amount of rest.At the end of this process, usually less than 40 competitors remain in a pool that final contestants are chosen from.