OK, so I want to make a few disclaimers before I talk about drum rooms, shields and drummers. I hate small enclosed spaces to put a big sounding instrument like a drum kit in. I also think close micing and tight gates on drums diminish the fact the a drum kit is a singular instrument and sounds much better in an open room with just a few mics. (I have heard this done very successfully in certain conditions) I don't like adding 3 layers of reverb to achieve an open sound out of a kit that is squashed in a small room and miced heavily with a bunch of channel processing.
But, I do it anyway. Why, because that is what it takes to make the big expansive sound of a well played drum kit to sit in a mix that is limited to 92-94dB in a 9,000 seat round church. Part of our issue is that the closet seat to the drums is about 25' away. The furthest seat is about 125' away and 95' high. If we were to have the drums in the open air any cymbal splash would mask the vocals for about 80% of our room. Even if the drummer is being subdued in his playing.
The certain conditions that i referred to earlier usually include a proscenium theatre with lots of 22oz curtain legs and lots of room for the sound to go before it gets to the audience.
My point is this. Most of us work in facilities with less than ideal acoustics. We all have to do what is necessary to make the worship experience for our congregations the best that it can be. That frequently means using techniques that are less than what we would prefer.
Peace (Phil 4:7)