Funny analogy, in that when the high caliber shells start raining, most forms of cover won't make a difference. The ones that will, are not something you want to stay behind on days when you're not being actively bombed. In fact, keeping you behind such protections is by itself a military tactic - it lets the enemy roam freely and maneuver around you.

But the basic flaw of this analogy is that it implies you're at war, and your system is always in battle.