On 19 April, Yorke wrote on Radiohead's website that they had finished recording. Having completed over 20 songs, they considered a double album, but felt the material was too dense. Instead, Radiohead saved half the songs for their next album, "Amnesiac", released the following year. Yorke said Radiohead split the work into two albums because "they cancel each other out as overall finished things. They come from two different places." He observed that deciding the track list was not just a matter of choosing the best songs, as "you can put all the best songs in the world on a record and they'll ruin each other". He cited the later Beatles albums as examples of effective sequencing: "How in the hell can you have three different versions of 'Revolution' on the same record and get away with it? I thought about that sort of thing." Agreeing on the track list created arguments, and O'Brien said the band had come close to breaking up: "The track listing of "Kid A" was really fraught. That felt like it could go either way, it could break ... But we came in the next day and it was resolved." The album was mastered by Chris Blair in Abbey Road Studios, London.