Using seconds is or at least seems convenient for developers but you can not represent many meaningful recurrences. Birthdays? No, because of leap years. A meet

Using seconds is or at least seems convenient for developers but you can not represent many meaningful recurrences. Birthdays? No, because of leap years. A meeting every Monday at the same time? No, because of daylight saving time. Essentially everything beyond »every hour« is broken because one hour is the largest time unit with a fixed length - day, week, month and year do not share this property but are the units most recurrences are based on.