The most I ever did in a row without a rest day was 9 days. After a day of rest, I could tell that's not a pattern I should do. I used to do 5 to 6 days/week, but since I ride longer distances and several factors have interrupted riding, I usually do 4 to 5 days/week(sometimes even as low as 3). I don't like to do fewer than 4/week and generally only do 3 in a row.