There are years with 50, 51, 54 or 55 weeks. (For example in the years from 1900 to 2200 there are 120 years with 51, 92 with 55, 70 with 50 and 19 with 54 weeks.) https://flussbettnerei.net/Calendar-Program.html
The old Sun-Moon polarity can be considered to be overcome with the (gregorian) determination of Easter, because you have to wait for the equinox as a point of the solar cycle, then the next full moon as one of the lunar cycles and take the next Sunday – free from both systems. Starting the calendar with Easter you get a calendar whose singular years neither use months nor fullfills the solar year.
The epoch of its era is the original Easter day, that means: Sunday 27 of March 2016 is the Sunday 1/55 of 1983 (because this year 1983 has 55 weeks). (Without starting a disussion about the historicity of the date – most people want to see most time the difference of 33 years.)
The idea for the calendar style is based new on a calendar attempt of Rudolf Steiner, described in the lecture “Secrets of the kingdom of heaven in parables, in actual form”, hold in Cologne on May 7, 1912, for members of the Theosophical Society.
The concept is not new at all: till the middle ages, a lot of beginnings of the year were in use – this beginning at Easter among them. Only in 1691 Pope Innozenz XII. (1615–1700) recognized the 1st of January as the new year’s beginning.