each covering seven in-game days

I saw this and went "I thought it said once a week". But you are correct, it's every seven days. Which is ridiculous as the Forgotten Realms (the setting of most modules) uses a 10 day week. This means that any further modules are going to need to modify that timeline.

Either way, it means that tracking the date for your adventure becomes mandatory, rather than optional. My first time DMing (Lost Mines/Icespire merge) I didn't bother with the date, because it wasn't necessary, but I tracked days on a calendar for Dragon Heist.

It's this extra work that makes me hesitant about the bastions. Keeping track of the date, the rooms, the number of hirelings, running the random encounters. The random encounters mostly seem like distractions, especially when the party is away from their bastion.

Player: "who is attacking me?" DM: "this group" Player: "well I'm going to leave Avernus and hunt them down next session"

And each player is supposed to have their own bastion! Sure, the standard group is 4, but we often hear of larger groups. And the combined bastions are combined in story only, they run as two separate locations for everything apart from the encounters.

Whatever happened to "don't split the party"?

I'm glad you like the idea of the system, and please don't think any of my negativity is directed towards yourself.