Q. Is a period of Fifty Years or in general that amount very relevant and significant in Judaism?

A. Talmud Rosh Hashana (21b) teaches that fifty are the Gates of Understanding that were created in the Universe, forty nine were given to Moshe, as the posuk (Tehilim 8: 6) teaches: “You have made him slightly less than divinity, and You have crowned him with glory and majesty.”

Fifty are also the days that we prepare after Pessach for the receiving of the Torah. Fifty amos is also a very common distance used widely in the Eiruvin and separations of towns etc. It is also common on penalties paid.

In Pirkei Avos (5: 25) we read that fifty years is the age for giving counselling.
On question 1235 we wrote that Some Poskim do write that there is a fifty year limit for maintaining a yortzait and reciting kadish. (Yalkut Yosef, kivud Av Va’em 13: 61, Nitei Gavriel ; Avelus 2: 77: 22 n. 40, quote Hedras Kodesh (p. 72) in the name of Mahara’Sh of Belz zy’a, Chaye Yitzchak, More Horim in the name of the Divrei Chaim and others).

Nitei Gavriel explains in their name, that after that time the neshama has already found its tikun (mending and correction) and has reached its correct most elevated place in Gan Eden. He also quotes that the fifty year period reflects the time frame that the Talmud (Shabbos 89b) considers common and correct for the liability of sins. (See Ben Ish Chai, Behar).

On question 1638 we wrote that Horav Shlomo Miller Shlit’a quoted a Rambam (Korban Pesach 1: 11) that a chavura or group eating the Korban Pesach could include as many a fifty people. Since both men and women are ordained to participate and they have to be seating in one place without a mechitza to be considered a single chavura, it would seem that even on a large family Yom Tov meal including guest or neighbors (as the posuk mentions), no mechitza is necessary.

And there are many other significant mitzvos and Halacha cases were the number fifty is mentioned as significant.

Rabbi A. Bartfeld as revised by, Horav Dovid Pam, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit’a