A frame every 30 seconds is 2 frames per minute, 120 frames per hour, more or less 1200 frames in a ten-hour day. So we go through a card per week (and during the winter, the battery usually died, after which the camera never came back on the next day).
I'm joking about the chimney coming down. We had a rough winter, and a very wet spring, here in the Northeast USA, so we are behind schedule by a couple months. But we're lucky to have another house to live in, so we're in no particular rush. We're looking forward to moving into a very "green" house by fall.
We'll need the contractor's help to install the camera indoors when the sheetrocking goes on, although that would make great footage. I expect they'll knock off a wall in a couple hours, so if they don't move the camera to follow the action, we won't see much indoors.