When perpetual calendars are too complicated but a simple calendar just doesn’t cut it anymore because nearly half the months have less than 31 days, it’s five adjusts a year too many for some. But don’t fret, there is a middle ground between the most basic calendar watches and complex perpetual calendars. The annual calendar automatically adjusts for each month with 30 or 31 days, meaning just one adjust for the owner in February. Here’s a brief history of the complication.