BobSo you are saying that even though the original calculated Bulk totals (+ any extra brought in through times when the "ring" is technically broken) are used up then the Building Destruction Phase begins. However, extra Bulk(uncountable for progress calculation) may be there and still count for Settlement upkeep at Target Settlement level or as close as can be maintained?
Will a settlement not be pretty much a level 9 or 10 (for counting building hps) by the time that all the Bulk cushioning is gone and the Structure Destruction phase is under way or does the settlement keep it's level as recorded when the siege started?
All the calculations that use Settlement Level will get recalculated if the Settlement Level drops, and there's a good chance it will start to drop once the bulk destruction phase is finished. However, while the rules for replenishing bulk limit the amount of bulk resources that can be used as part of the bulk destruction phase, there's nothing blocking the settlement from bringing in additional supplies to pay for upkeep. Also, once the bulk destruction phase starts destroying really large amounts each day, it may be in the settlement's interest to remove the last bits of bulk from the upkeep vault so that it doesn't all get destroyed, so that the structure destruction phase takes place with higher defenses.
To be honest, most settlements reaching this point should have seriously considered suing for peace at an earlier stage, or may have already abandoned the settlement and preferred to force the attackers to go through the motions before taking over. If the attackers managed to surround you, and can keep you surrounded long enough to deplete your initial bulk resources, it's going to be pretty hard to break the siege during the structure destruction phase. On the other hand, the defenders can make the attackers pay for their victory, in siege costs, destroyed buildings, and in the gold needed to keep the buildings they preserve, and this seemed like a reasonably balanced way to give the defenders some control over how much that will cost the attackers. In the end, pushing those costs on to the attackers may be worth giving up the potential advantages of a negotiated settlement.
In other words, the settlement may reach the Building Destruction Phase but may still be of higher level(for this phase) than a settlement without remaining Bulk reserves… ?
Am I grasping that right?