I totally agree and feel the pain you go through in order to host some FFA or any training in your own apartment. I just got a comment which is:
Instead of making it (all jobs can damage eachother) To add a code for example /toggleapartmentdamage when you want to host the FFA training or whatever it is and turn it off for any other training that might require you not to shoot.
Which can avoid any mess might happen by accident or not.