Adopt the Symmetry454 Perpetual Calendar

The Symmetry454 calendar is a simple perpetual solar calendar that conserves the traditional 7-day week, has symmetrical equal quarters each having 13 weeks.
Every Symmetry454 year, quarter, month and week starts on Monday and ends on Sunday.
Holidays and special days are permanently fixed.
Non-leap years have 52 weeks = 364 days. Leap years, which occur at intervals of 6 or 5 years, have a leap week appended to December, as week 53 of the calendar year = 371 days.
The Symmetry454 calendar is perpetual — a permanent copy can be reused every year.
There are no intercalated or “null” or leap days outside of the traditional 7-day weekly cycle.
Its symmetrical structure paves the way to simpler, aesthetically pleasing calendar designs.