Annual calendar years. An annual timepiece calendar is less complicated and expensive than a perpetual timepiece calendar, which will not require manual adjustment till 2100. That year will not be a leap year, even though its number is evenly divisible by 4. Ancient calendars (static) may always have been annual, even after the length of the calendar year was fixed at (avg.) 365.25 days by the Julian Calendar (46 BC). Early Romans observed an 8-day market week, called the nundinal cycle, until the seven-day week was adopted during the reign of Emperor Constantine the Great (306-337). A goal of modern calendar reform
Middle-earth calendar more generally: The Elves also have a regular 365-day solar year called "coranar" meaning "sun-round" or more commonly "loa" meaning "growth". The Elven year, which began near the northward equinox, is divided into six seasons or 'months' which consist of four 54-day months and two 72-day months. Five or eight extra days outside the seasons make the length of the "loa" 365 or 368 days. Most years are 365 days, but every twelfth year is 368 days, resulting in an average year of 365.25 days with the additional suggestion that the 'Reckoning of Rivendell' made a further correction by omitting