Very nicely done and (as has already been said) very well painted.
I have a couple of the rubble moulds and agree they're excellent and pretty versatile. And the casting process itself is straightforward, once you've got the hang of it.
But you're right about the time factor - anything except a small building does take a while. I'm looking at a three-quarters finished ruined house right now, that's been three-quarters finished since Christmas...