Do any consoles compensate for that or panning and etc? Or do we assume this is always true?
I won't say that no consoles compensate for it, but none of the ones I own do (Avid, Midas PRO, Yamaha M7 and LS9) . If you set up a stereo subwoofer bus then they do but at that point you are eating up an extra bus, and an extra drive line etc.
Plus you will have the same problem with front fills possibly, depending on your source. I usually try to derive the front fills from the matrix off of the left and right bus, each set at. -6. Though as I am not deriving the front fill matrix from a mix of stereo and mono channels, this is less of a big deal.
Jason