I've been considering a big campaign game I played a while back. Early in the adventure (around level 1 or 2) we acquired a house for the party to stay at. This was provided by the DM himself, since the module didn't provide any common living area for the party, despite the vast majority of the adventure taking place in one city.
Anyway, I'd somewhat considered it in terms of a Bastion, but forgot that it could be built as a combined Bastion. There's been tons of analysis posted in the last few weeks, but almost all of it seems to consider things only from the perspective of a single player, and I'd gotten into that mindset myself.
So, the abandoned house that we took over had a large living room, a kitchen and dining room, a few bedrooms upstairs, a back yard, and a basement for storage (which we later found also had a secret entrance into the city's sewer system). Fitting it all together, we could have constructed that with four of the player characters.
Roomy: Living room, main bedroom, basement, back yard.
Cramped: Kitchen, dining room, two small bedrooms
There was no washroom. We had a tub out back we used to scrub down in. It was in a poor neighborhood in the city, a bit above outright slums. No walls or guards or whatever, and of course we never built it up with stuff like this Bastion system. However at its base, the party could have created this with the proposed system.
As I said, we got this around level 1 or 2. There is no reason to gate access to basic facilities, and with characters combining their free rooms, it's relatively easy to make a useful residence or similar gathering spot for the party for your early levels.
This could easily be done as an old theater (bard party), a startup thieves' guild, a trade warehouse, a rickety ship, or various other constructs that provide common ground for further development. And I think it's only later levels where the party is more likely to split up into individual Bastions, such as a wizard's tower or a knight's keep or whatever.
So rather than think of the combined Bastion as a secondary option, what about approaching it as the primary option?
So, a party of four or five, with four contributing to the combined Bastion, has some sort of residence built up in the early levels, and at level 5 is allowed two special facilities each. What does that look like? Assuming a party of four...
Level 5
Garden x2, Library, Sanctuary, Storehouse, Workshop, Smithy, Barracks
Suddenly it's not a strain to build something expansive the way it is for a single character.
GP earned per week: 80 (assumes one garden makes Potions of Healing while the other makes stuff to sell)
BP earned per week: 20 (no real value in paying for advantage at this point)
You could get one common magic item each week, giving the entire party one common item within one level, with BP left over. You could get a couople uncommon magic items per level, giving the party one uncommon magic item each over about 2 levels.
Level 9
Greenhouse, Laboratory, Sacristy, Scriptorium, Teleportation Circle, Trophy Room, Training Area, Stable
Convert one Garden to a second Storehouse. Enlarge the other Garden. (Pays for itself in a couple levels.)
GP earned per week: 500 (Greenhouse makes potions, so the Garden focuses on money)
BP earned per week: 48 (or 56 if you spend 200 GP on the 1d6 facilities)
You could get one rare magic item every 5 weeks, or 3 rare items every 2 levels for the party.
Level 13
Archive (enlarge), Meditation Chamber, Pub (enlarge), Reliquary
GP earned per week: 3850 GP (double action on improved Storehouse)
BP earned per week: 66 (or 85 if you spend 500 GP on advantage on the rolls)
This would allow one uncommon magic item every week, one rare magic item every 3 weeks, or one very rare magic item every 4 weeks. The party could get one very rare magic item each over a couple levels.
Level 17
Demiplane, Guildhall, Sanctum, War Room
GP earned per week: 8100 (improved Storehouse, Guildhall likely provides 500 GP)
BP earned per week: 88 (or 117 if you spend 600 GP on advantage on the rolls)
That would take 2 weeks for a rare magic item, 3 weeks for a very rare magic item, or 6 weeks for a legendary magic item. All four party members should have a legendary magic item by level 20.
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Overall, it looks like a party of 4 that built a combined Bastion would be able to get one instance of the best magic item at each tier within about 2 levels of reaching that tier. (This will likely be slower in practice due to having to use Maintain orders some of the time.)
A decent amount of money can also be made — an overall improvement for the party of between 5% and 25%, depending on level and tier. Of course you're also giving more ways to spend it.
When viewed as a collective party project, this feels like it works a lot better than how I viewed it previously.
