As you mention, it depends on what the situation is inside the room in terms of cover. The type of construction is also a factor. You also have to consider what armament the bad guys are packing.
I'd think using a dresser full of clothes for cover against pistols in an older home with lathe plaster walls would be fairly 'safe' as opposed to a home constructed of sheetrock.
If you have a plan to defend a specific room, it might be appropriate to consider how the room is furnished and how things are arranged.
I don't know how much time you've spent clearing houses and doing building searches, so your experiences may be different than mine. In my experience no matter how swift, silent and deadly you are trying to be, the bad guys know you are coming. A way to circumvent that would be to have Alexia turn on all your entertainment stuff to cover noise.
So, at one point we lived in a quad level house. All the bedrooms were on the upper level and could be approached only by going up seven steps and walking down a hallway. In considering defense, the first thing I realized was that the only way to search the house, aside from exiting my bedroom via a window and re-entering the house, was down the hall. I'm sure you've heard the term fatal funnel, correct? So thinking about it, I figured to get the kids into the master bedroom and have them sequester themselves in the porcelain tub in the master bath. I figured I would post up at the door to the bedroom and position myself in a prone position paralleling the hallway. This put the porcelain tub in the kid's bathroom in position to offer me cover. I'd then shoot anyone coming up the stairs from an unexpected position. My one concern was that it was merely three steps down to the level below and that a bad guy could shoot up through the floor.
My point is the home's floor plan plays an important role in determining your ability to search/more with a likelihood of success.
My idea was the bad guys wouldn't dictating the direction of the fight, I would be dictating the timing of the ambush.