Re: Once robbing starts, will they keep going until the robbed hive is empty?
Yes, the robbers are merciless to the week hive. Rob until the honey is gone or the hive defends itself.
Best solution is to make an entrance reducer with the entrance one inch deep and opening 3/8 high by 1/2 wide and place on a flat entrance board. This creates a 1 inch long tunnel, if you will, that is not much larger than a bee(two bee widths) and one guard/very few guards can monitor incoming bees.
The robbers, in my experience, seem to figure out the robbers screens.
If you always do what you always did, you'll always get what you always got!