Each quarter has 3 months, with the following lengths: 30 days, 30 days, & 31 days, in that order. There have been a number of . Its advantages are: 1. * With all months 30 or 31 days long, the months are as uniform as is possible with 12 months. 2. * For a given same year-start day, the 30,30,31 months' starting-days have the least possible maximum departure from the starting-days of the old Roman months. 3. * This ordering of month-lengths divides weekdays most evenly between the 3 months of a quarter.