40 Exercises, Opus 337
By Carl Czerny / ed. Maurice Hinson
Each piece of Op. 337 consists of various sections of one to several measures, each concluded by a coda. Czerny's own instructions above the studies read: 'Each repetition should be played 20 times without interruption,' or other numbers of repetitions. 'Daily Exercises' does not mean that all 40 studies are to be played every day, but the composer recommends that about one hour be devoted to studying part of them every day, requiring about three or four days to get through all 40 of them.