Only one dungeon in odd numbered patches

[Moomba33]

2.0
3 dungeons -> 3 months -> 0 dungeon -> 3 months -> 3 dungeons -> 3 months -> 0 dungeon = 3 dungeons every 6 months

We didn't have any patches without dungeons in ARR.

2.0: The Wanderer's Palace, Amdapor Keep. Castrum Meridianum and Praetorium if you want to count them.
2.1: Pharos Sirius, Copperbell Mines HM, Haukke Manor HM.
2.2: The Lost City of Amdapor, Halatali HM, Brayflox HM.
2.3: Hullbreaker Isle, Stone Vigil HM, Tam Tara HM.
2.4: Snowcloak, Qarn HM, Sastasha HM.
2.5: Keeper of the Lake, Wanderer's Palace HM, Amdapor Keep HM.