On average two boxes a week. Five kids( three have moved out but are always on a fridge raid) and the occasional short term fostering.
These size projects are easily achived from a single box. The small single engine plane I did recently actually left enough card from one box to make a second plane.( one the fokker tri motor thread.)
Only roof tiles and the vsf spaceship have been really heavy on card . But once your neighbors lean your using cereal packet card you can find yourself inundated hense the sudden flood of builds