The way Keiko is carried out in Oozumou differs significantly from Amateur Keiko, especially in the timing.
For Rikishi in Oozumou, Sumou is their Mission, a profession and everything comes second to it. Thus Keiko is the most important activity of the day and it takes quite a significant part of the day.
Keiko starts in the morning, at around 5:30 AM for the Rikishi in the lowest Divisions. Hence the term Asageiko - Morning Keiko.