As I’m mixing things that I (and others) recorded I notice that sometimes the room mics and overheads are unbalanced.
For instance, with overheads, the snare can be a little off-center, and sometimes even the kick is leaning to one side more than the other. I usually place overheads as a spaced pair and not in XY so the overheads really are just there to capture the cymbals. However, because the OH are a spaced pair and are positioned above the cymbals, the kick and snare end up off-center. It’s probably possible to place a spaced pair so that they capture the cymbals but the rest of the kit is still balanced, but these things can be fixed in mixing too. A high pass at around 250Hz would basically eliminate the kick, and a really fast compressor will work to eliminate the snare from the overheads without washing out the cymbals.
I noticed that some of my room mics have a similar issue – the kick and snare aren’t centered. The way I almost always position the room mics is on the floor and so that they create an equilateral triangle with the kick. This should guarantee that the kick is centered, but I guess sometimes the microphones aren’t symmetric with regards to the kick. However, this positioning will always lead to the snare leaning to one side or the other. Since the room mics serve as a full image of the drum kit, this isn’t something that can be fixed during mixing. So maybe a better method is to keep the microphones symmetric along the line that runs between the kick and snare. One way of doing that would be to position the microphones in front and behind the kick. Another is to have the microphones in a non-equilateral triangle formation.
With all this being said, I haven’t really noticed the drums being asymmetric once the close mics are brought up, so maybe this isn’t something that a lot of time is spent on during quick sessions.