Many like to set up a scenario by saying they will retreat to a safe room.
Is your safe room bullet resistant?
I cannot imagine thinking that one would be able to "plan out" one's "shooting lanes".
One will have to shoot at the target when need arises, and not a moment later, and from wherever one might be at the time.
So, the scenario is that from any angle you could be fired on? Downward thru the upstairs floor? From outside the house low next to the window you might be crouching near?
I've had my training in urban warfare, punching thru sheetrock to gain access into the next room is light exercise. Unless you fasten said bookcases to the studs, a broom handle can penetrate the rock and push them over, all while the intruder does his work with relative impunity - it protects him as much as you.
The vast majority of intrusions are the two listed incidents I mentioned - them's the facts. What's left are the very small minority, and not checking the address ranks really high as the cause, whether police or thugs. My take on this is armoring up the interior of the home in a last ditch stand is pretty desperate, when the smarter choice would be an extended exterior defense where the attackers are stymied or stopped before they even get in the door.
Plenty of options there, the normal ways to constrain entry has been going on for centuries. Town walls, moats, gates, use of the existing landscape like hill tops, etc. Now we see gated communities, apartment buildings have been using entry request systems for over 50 years, doormen are still common for those who can afford them.
Where all the "home invasion" comments come from are suburban residents with no historical education or military training. What I keep reading is responses literally "made up" with a very narrow view and apparently no background.
It was noted in another thread that a rural home was broken into while the resident was away - they left the back door open. It brought to mind a relative who lives in a similar situation - there's a driveway "chime" when something sets it off at the highway, vehicle or walker, which alerts the dogs (friendly as they are) that family is coming home, and the barking starts.
Point being, none of the common sense things are discussed in a rush to deeply analyze how often someone should practice donning body armor when awakened randomly from a deep sleep by an intruder staring down over you in bed. <----- Which is exactly the sort of fantasy talk these threads always degenerate into.
Let's back up to square one - just what are you doing to invite thugs to bash down your door and attack you? How did they even arrive there, what got their attention, and what can you do to explicitly prevent them from even being a problem?
You can only do so much, prevention is a lot better than a last ditch effort. Sure is better than having the cops or some thugs parade your wife and family around in their jammies while they insult and beat you. We need to start thinking ahead of the curve - not reactively when doom is on your doorstep.
Of course, that is a lot harder sell on a gun forum, because we can't discuss what caliber, what type gun, and what your shooting lanes will be. There will be shooting lanes, of course, what you need to do is understand them and create them, not be subject to a complete lack of planning.
In the military there are plenty of options to exercise - filling the hallway with concertina wire isn't something we would easily do at a moments notice, but is there something you CAN do to slow them down? That bookcase would do a better job if it was laying across the hall opening to slow them down. Of course, if you can think of ways to enable that, better to do it at all the points of ingress and stop them before they even get in.
Sometimes it just might be as simple as NOT putting out all the cool new boxes the electronic toys came in out at the curb after Christmas. Ya know, the cops have been telling us stuff for years and we simply won't listen.
Nitpick me all you like, just know that your best interests are in mind. Don't waste your efforts in things that are too little too late. Get your defense in order up front.