Having never built homes I’m guessing here, but once framing starts they keep moving because raw wood is exposed to the elements and they have already made “reservations” so to speak with the various subcontractors, scheduling their time in advance, there may be a financial penalty if they cancel on short notice. Plus they already paid for the models, the sales staff, permits and advertising, shuting down in a falling market is probably a bad idea. What they will do is delay the next phase until a percentage of the released phase is sold and discount the unsold stuff. It seems to be a double edged sword because if they sell three houses and then discount the other three, the first three buyers will cry foul and they haven’t really bought, just reserved with a deposit. It is my guess that most builders have a lot of money invested by the time the foundation is poured that they might as well and finish and get paid even if it is for less than what they had hoped for. Plus they have no guarantee they won’t have to lower prices further, they probably want to get what they can while they still can since the average Joe may not follow the market like a pigintonian.