Leap years occur once every four years and are necessary because, if every year we counted 365 days, after 12 years there would be a difference of 3 days, and there would be a major change in the seasons of the year, to solve it is added one day every 4 years, by compensating for the gap between those 5 hours and 56 minutes that we have over every year. It is added in February, because it is the shortest month in the calendar. Âżhow many days, weeks, months have a year according to the Inca calendar? this yearbook consisted of twelve months of 30 days each, in turn, each month had three weeks of 10 days, resulting in a year or huata of 360 days.