Will the Courses of Priestly Service Give Full Years? No.

First of all, the courses are in cycles of 24 weeks which then start all over again.

Second, no natural year is only 48 weeks long.

Third, the mean length of Hebrew calendar years are the length of same number of natural years added, with little discrepancy in shorter periods.

This means, any reasonably cycle of years will have clear discrepancies from cycles of 48.

But even more, Unlearn the Lies presenter Lex stated that three feasts were excempt from the cycles, so that makes an overall cycle of 51 weeks. He is presenting his "annual cycle" in 7:18 to 7:38 where he states all priests served Passover, Shavuot and Sukkot.*

And, this one also gives no correspondence year by year.

This means, the courses of the priests clearly vary from year to year.

I will first deal with natural years.

365.25 * 7 = 2556.75 (2557)
2557 / 7 = 365.2857142857142857 (365)
365 / 48 = 7.6041666666666667 (29 weeks left, so extra "half year" cycle of 24 + another 5 weeks)
365 / 51 = 7.1568627450980392 (8 weeks left)

365.25 * 21 = 7670.25 (7670)
7670 / 7 = 1096
1096 / 48 = 22.8333333333333333 (40 weeks left, so 8 weeks short of a 23:rd cycle in 21 years)
1096 / 51 = 21.4901960784313725 (25 weeks left, so an extra "half year" cycle and an extra week after 21 "full year" cycles)

365.25 * 19 = 6939.75 (6940)
6940 / 7 = 991.4285714285714286
991 / 48 = 20.6458333333333333
992 / 48 = 20.6666666666666667 (after 20 "full year" cycles in 19 years, there are 31 to 32 weeks left, meaning another "half year" cycle and 7 to 8 weeks left)
991 / 51 = 19.4313725490196078
992 / 51 = 19.4509803921568627 (after 19 "full year" cycles in 19 years, there are 22 to 23 weeks left, that is one to two weeks short of another "half year" cycle)

365.25 * 24 = 8766
8766 / 7 = 1252.2857142857142857
1252 / 48 = 26.0833333333333333 (26 "full year" cycles and 4 weeks)
1252 / 51 = 24.5490196078431373 (24 "full year" cycles, one "half year" cycle and 4 weeks)

365.25 * 48 = 17 532
17 532 / 7 = 2504.5714285714285714
2504 / 48 = 52.1666666666666667
2505 / 48 = 52.1875 (52 "full year" cycles in 48 years and 8 to 9 more weeks)

365.25 * 51 = 18 627.75 (18 628)
18 628 / 7 = 2661.1428571428571429
2661 / 51 = 52.1764705882352941 (52 "full year" cycles in 51 years, and 9 more weeks).

5760 (1999–2000) had Rosh Hashanah on Sept. 11. It seems this date does not recur exactly between 1999 and 2050. But 10th and 12th do.

Next year (2000 - 2001) had it on Saturday, September 30.

September 30 recurs for 5769 (2008–2009), 5780 (2019–2020), 5799 (2038–2039) if it happens, and I have not taken into account October 1 and September 29.µ

So, while year to year is clearly not a natural year, over the years they average into same number of natural years.

This means, no set of Hebrew years can have either 48 or 51 weeks as full annual cycle.

This means, if Lex calculates it out as if first division beginning in first Sabbath of the month of Aviv always means the same course, namely the first lot, that of Joiarib, I Chron. 24:7 would be wrong. The Mishnah information would rather mean that the first lot of the year - Joiarib one year, the one King David made the system, someone else next and so on. And this means, as Catholics have stated, one must count backwards from a known date with a known course, which we have for destruction of Temple.

THIS is how Catholics calculated that St. Zachary served second week of Tishri./HGL - and Merry Christmas!

* Was Jesus really born on December 25th (Christmas Lies)
UNLEARN the lies | 20.XII.2014
https://www.youtube.com/watch?v=hJ-FG_zDhW4&t=359s