As someone who works in construction, I have to say that rolling a few sheets of barrier or framing a couple extra walls really doesn't take that long or cost too much. It's on the order of $5k or less and a couple days work, for both materials and labor.

What does cost time and money is getting permits, planning approval, inspection, etc. Not that those are unimportant, but any delays are certainly not on the construction crew's behalf.