I personally like it. It was difficult to keep track of ‘2nd Monday of month vs 4th Thursday of month’ etc. Now it gets more clear, and less down time which for me personally is good thing - I like when stuff happens, those weeks without anything felt really boring.
The order seems to be from the least interesting summons early in month (old HotMs, Atlantis) to most exciting summons later in month (new Challenge events, new Season). Nothing that would bother me personally, unless we return to seeing useful HotMs again that feel like ‘must haves’. Currently I am fine skipping summons early in the month and focus later on if there’s anything useful for me to hunt for. And if HotM doesn’t appear in those last days of month, no tragedy - they are all trash anyway. Besides, as stated in the OP, there may be some months where the schedule moves weirdly and one event happens twice during the same month. I don’t mind that personally, can even help (it will be easier for event to happen partially one month, partially the other month - so you can focus your summons depending on HotM preference).
I guess Tavern is waaay too long because it rotates with Ninja Tower so they have to dedicate same amount of time to both. Feels like a waste of space there, perhaps time to rework ToL to include 50 stages as well?
Season 4 starting in March… Wow, surprising I have to say. A bit worrying that beside the heroes, no bit of it was in beta yet. I expected May-June. I hope quality will come with this rush. I have to say as much as I liked Valhalla heroes, artworks and story, the gameplay was superdull. Using another campaign only as an excuse to sell new heroes will definitely not make me love this game more. And the fact no new mechanic was tested in beta is quite a sign there will be no new mechanic…