As mentioned in another question, we have a few fast days, mostly connected to the destruction of the Beis Hamikdash. Yet, which one?
- Tzom Gedalya, 10th of Teves are exclusively 1st Beis Hamikdash related
- 17th of Tammuz, according to the Bavli Taanis 28b was exclusively 2nd Beis Hamikdash (and we don't fast on the 9th which was when the walls of Jerusalem were broken)
- Tisha Be'Av - Both.
Why can't we be consistent? Either fast on the 9th, or replace Tzom Gedalya and 10th of Teves with parallel 2nd Beis Hamikdash events?