Are you planning on scattering cover around your home so you can stage a running fight? Or do you just want cover in one safe room?
Every house layout really has just one or two "most likely" lanes of fire, given your floorplan, points of entry, and living arrangements. Create some kind of backstop behind those "most likely" areas, and make sure everyone in the home has something solid to duck behind in their own bedroom(s), and you're a lot safer than you were before.
It's not that major an undertaking, if you remember that almost anything is better than nothing and that just because you can't do everything
doesn't mean you should do nothing
to improve matters.