From the SF Gate: "... Natalie Coughlin built her fame in the water, stroke by tedious stroke. She swam between 6,000 and 7,000 yards per practice - once or twice a day, five days a week, for the year leading into the Olympics in August. Her talent and training led to six medals in Beijing, the most ever by a U.S. female athlete in one Olympics. ..." [Link]
Those distances have a nice to ring to them. One-hour in the morning, another hour in the evening would actually feel pretty good.