S2 of SAO is 3 arcs.
- GGO
- Caliber, which is like 2-3 episodes
- Mothers Rosario
Rosario takes part in Alfheim, but it focuses on Asuna and another very good character, so if you can power through Caliber, I highly recommend giving it a 2nd try just for it.
And it’s worth watching just to be able to watch Alicization, which is doing a great job so far and I’m stoked for each new episode.