This is not how I understand it. With better approximations of the year's length, the notion of the Sun returning to its original position disappears. The simplicity of the 365.25 approximation is the essence. It is not at all a pragmatic choice.
The 28-year cycle is not an approximation. It is exact, just like the cycles of 7, 12, and 19 years are exact. Physical reality reflects these numbers in a slightly distorted fashion. There are approximately, but not exactly, 235 months in 19 years, giving 7 leap years and 12 regular years. The year is approximately, but not exactly, 365 and a quarter days, and after 28 years the 'quarters' approximately, but not exactly, add up to a week. However, physical reality is not the norm. It is the mirror through which we see.
What we see through the mirror are exact symmetries of the 6000 years of Malchut. Zeir Anpin has interfering cycles of lengths 7, 12, 19, and 28. The sum is 66, twice Vav. Gevura has 7, Chesed has 12, Yesod has 19. Tiferet, Netzach, Hod together have 7 times 12. Each has 28. Every one of the 28 years is associated to a letter of the Aleph-Beth. Years 1-22 correspond to the regular letters of the Aleph-Beth, years 23-27 correspond to the five "Sofit" letters, the last year is Aleph Sofit. At every Birkat HaChammah a new "day" of history starts. Its middle five years are its essence, the height of the day.
The last four cycles brought us the success of the zionist movement, leading to the Balfour declaration, the rise of Yemach Shemo, leading to the Holocaust, the liberation of Yerushalayim, leading to the Yom Kippur war, and the Oslo rebellion, leading to the Oslo war. The pattern is clear - May we merit to see the final Geula "today."
מז
