This is theoretical. Everything I say here is a hypothetical guess, so it might be inaccurate.
I just realized the King's pattern of rollout phases nowadays. Some of those features took you so long, probably like 1-2 months, or even years, and you even get desperate of wanting it. Well, what if I told you, this might be because of the player's behavior and activity?
As you might observe, rollout phases from before are very fast. That's because they didn't care. But now, they made it stricter. I think I know why now!
You see, rollout phase / A/B testing is when that feature is only available in some players but not all players. It's essential, because this phase allows developers to gather feedback from players. But they didn't just record their feedback, they also record player's behavior and activity, and also their reactions.
That means rollout phase nowadays only gives to very small population, probably 5-10% of the players. And if the player's activity drop even slightly, they need to stop releasing the feature and then make more improvements. Now, they will test it out again after improving it. If the player's activity from that feature rise, they will now expand it very slowly. Now going to 20%, 30%, and 50%. If the percent drops down again, they need to remove it again and start over from 5-10%, basically over and over. The goal is that players must satisfy with that new feature and players are actually good at it. If it was successful, then the global release was ready.
That's why you might thought why Soda Islands take so long, why are these new events faster than Soda Islands? Now you already know, because of just the rollout phase itself ✌