I liked the 13 period calendar they had from 1928 to 1989.
* All months would have the same number of days (28), the same number of working days, except holidays, and the same number of Sundays.
* All months would have exactly four weeks.
* Each week-day would always occur on the same four fixed dates of the month.
* Quarter-years and half-years would be of the same length.
* The month would always end on Saturdays.
* A holiday would always occur on the same week-day.
* The date of Easter could be fixed.
* Yearly calendars would no longer be necessary, one fixed monthly calendar would be sufficient.
Nation's Business, May, 1926, p 42, 46.:
http://myweb.ecu.edu/mccartyr/eastman.html