Attempts have been made periodically to reform or replace the Gregorian calendar system that is widely used today. Some proposed universal calendar systems aimed to smooth out the uneven month lengths of the Gregorian calendar.
For example, the World Calendar divides the year into four equal quarters of 91 days each, with each quarter beginning on a Sunday and ending on a Saturday. An extra day at the end of the year, along with a leap day every four years, keeps this calendar aligned with the tropical year.
However, no major calendar reforms have been widely adopted globally. The Gregorian calendar continues to function adequately as an international standard. Some cultures and organizations use variations like academic calendars or fiscal year calendars for specific purposes, but the Gregorian calendar remains the predominant system internationally.
While universal calendar proposals have aimed to improve consistency, the Gregorian is deeply entrenched after centuries of use. Significant worldwide coordination would likely be required for any competing universal calendar to gain traction at this point.